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I'm looking at using epoxy doming resin on the rewind.
Does this sound suitable?

Probably fine, at least for outer coats.  Unlikely to penetrate between windings to fill between windings and core tube.  Something with much lower viscosity and lower surface tension would be better for penetration.  Need for penetration depends on your secondary volts/turn  I don't have enough experience to say if penetration is needed, not even for my own coils.

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I see UV curable ones on the market too but don't know what the quality is like.

There are fine UV epoxies, even ones hard enough to use for dental fillings.  I have no way to tell quality of any specific UV epoxy.  UV epoxies require a minimum light intensity for curing.  Low intensity can't be compensated for completely with long exposure times.  UV cured epoxy might be a good option for coating core before winding.  Will remain uncured plenty long for winding.  Add another coat after winding and expose to UV.  Cure is a chain reaction to some extent (depending on epoxy formulation).  I think epoxy under wire is likely to cure due to exposure of upper layer to UV even though not receiving any direct exposure.  Would need to be tested for any given UV-cure epoxy, however, or discerned from data sheet if available.

I think that it would be ideal for the resin to penetrate the windings, even if it had a lower viscosity, i feel it would have trouble doing so. Vaccuum impregnation would be the ultimate but very difficult and expensive for a coil this size.
My main concern was how the coil was lifting off the tube. It was almost like it had either overheated or expanded? Im not sure if that was the issue or if the wire was wound on too loose?

Yes UV curing resin would have the big issue of not getting enough light under the winding itself to cure, however it does go off on its own if given enough time, and a chain reaction should happen if only a handful of molecules get exposed to the UV or get in contact with the outer layer when exposed. Might be worth exploring this further.

Not too sure what others do with their coils, but definitely going with epoxy this time round.

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I also haven't heard of epoxy polyurethane before, I thought they were two entirely different things.

After some google searching, I am probably wrong here.  My apparently-incorrect memory was that Parks glaze coat was a urethane based epoxy and that such was common.  I find nothing now supporting that memory.

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It did cross my mind if control electronics could be partly to blame. My driver is loneoceans universal driver v2.7
One of the main issues I've had is shielding the computer and/or USB midi adapter.
The RF causes it to lock up and hang on a note.
Sometimes it's not quite bad enough to hang the unit, but it's causing some notes to sound like garbage at times.

I dont know if I need a longer fibre optic cable or try shielding the computer better.
I've got toroids on the USB cable that help, but it's not perfect and can't play music at full power.
Maybe a better midi adapter could help?

I've also had trouble with MIDI notes getting stuck on.  It isn't a hang of the electronics, but rather a disruption at the point when the key-release code is transmitted.  Playing the same note again will unstick the note on that release.  In my case, MIDI is coming from a keyboard (synthesizer) for live music.  It is difficult to determine if the disruption is within keyboard (MIDI source), communication link, or MIDI interpreter.  I ended up with grounded metal under keyboard with foil extending around back side and over half of top.  Placed MIDI interrupter within that shielding and powered both from batteries also within shielding.  Probably not all necessary.  Seems that the keyboard itself is most sensitive.  It is a large object with plastic housing.

What MIDI interpreter are you using?  Being in a hurry back in 2019, I purchased a kit from EVR.  It is not very good.  Some notes are up to 2% off in frequency.  Worse, more than two notes playing simultaneously outputs garbage.  Made my own soon after.

With my unit, the USB MIDI device would stop working and stay stuck on a note forever.
I have to disconnect it from the USB port to reset the thing or else it wont work at all again, seems to be causing it to lock up or something, but either way, tie computer stops communicating with it because starting another track does nothing to help it.
I have wanted to try it out with a keyboard over a MIDI cable but dont know how i set the channel on my keyboard to the correct one the MIDI controller is using.

My MIDI controller is called a "mini MIDI controller" see here:
https://sites.google.com/site/teslacoilstore/mmtcc
They seemed to be popular at the time I built my coil. I was also advised early on to add the toroids to the MIDI cable, as i was having issues right from get go. They do help, but its not a solution to remove it all, perhaps i need a better shielded box, tin foil is doing nothing.
Im interested to see what these new MIDI interrupters are like that will work with more than 2 notes at a time.
Great to see technology improving.

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For whatever reason, I was advised against epoxy at the time and told to go with polyurethane.

Polyurethane epoxy is available.  That's what I used after the two spray coats.  Common urethane epoxy is intended for coating wood table tops etc.

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When I operated the coil I also noticed that the streamers were quite whispy and fuzzy looking, not clean lines like I typically see. Is this a symptom of a damaged secondary, or could something else be at fault?

Could be either.  Might be worth scoping primary waveforms with existing secondary coil before repair.  See if they look normal, at expected frequency and with resonant energy transfer primary to secondary and back (at least when below arc voltage to minimize energy loss to arc).

This is the stuff I used, at the time it seemed a good product.
https://www.uroxsys.co.nz/pdfs/MCRGlossdata.pdf
Is the epoxy polyurethane you refer to a two part mix or single  pack?
I know people who own a paint shop and can get me an endless selection of products.
There is a clear resin I've seen that goes rock hard.
I was thinking another option may be to apply a thinned down coat that can penetrate the winding easier, and then apply thicker coats on top. This stuff I've got is rather soft and flexible, but hard wearing as its for floors.
It doesn't stick to the pvc pipe very well, I can peel it off.
My main concern is if my issues are IGBT damage, but i don't think they fail like that do they? Seems to only be giving issues since the coil has broken down.
Will be interesting to scope the bus again, I know I had it tuned fairly well at the time.

I've noticed some discoloration on the wire and not sure if it's corrosion on the enamel or something but had happened on its own during storage.
I used it the other night and noticed that some notes don't sustain very well and depending on the frequency, I.e higher pitched notes were not playing very well or with much of an arc at times.
I cranked the thing up to full power and noticed some pin prick blue Corona all around the coil, and seems to happen around these parts of the secondary that are discolored.
I could see upon inspection that it's now burned through the polyurethane, do I'm going to have to rewind this coil again
Could this have been the issue with the coil not sounding right?
I'm wondering it is possible that arcing across the secondary behind the winding where I can't see it?
I want to use epoxy this time round. It is moisture cured floor polyurethane.
Is there an epoxy that can be applied first prior to winding that  will dry within a few minutes and help set the wire onto the pipe?
There is nothing really holding this onto the pipe and it's actually lifting a bit in places it appears.
See photo.

Oh hey completely missed the comment, sorry about that

Nice to hear you like this project. The polyphony is entirely included in the midistick itself, it just sends the resulting on/off data to the coil. As long as it has an optical interrupter input it should be compatible
Keep in mind, that many notes on at the same time will sound best with a large maximum duty-cycle (I have mine set between 15-20%). If you reduce the limiter threshold (because your coil can't handle that high of a duty cycle) the coil will sound slightly worse.

Yes, if you want to you can have any number of channels playing notes, up to four different ones at the same time with any combination of channels. If a note on event occurs when the four voices are already playing a sound the least important note will be turned off again and replaced with the new one.

For multiple coils at the same time you'll need one midistick per coil. I am currently developing the my next generation of interrupters, which will also have a version capable of sending data to up to four coils though (that will prob be released q3-q4).
Mapping sounds to the coils is quite a bit than dip-switches though: you just use the midi pan knob to fade between the coils As if one was the left speaker and the other was the right one. You'll need to set that up in the software first, but then it can work on its own.

And yeah you can play pretty much all sid files out there
One exception though: some files use a hack to send audio samples through the SID chip, I don't support that yet. If a file has some sound effect that is just missing when you listen to it on a coil it is likely that it comes from samples.

Thats awesome, this should make it possible to play more MIDI files without anywhere near as much tweaking!
I always thought it was the limitation of the tesla coil itself with the number of notes. I probably am going to end up with a second larger coil soon anyway, so I could direct the bass track to the larger coil and send the main track to my current coil im using.
Definitely will be ordering one of these! SID music sounds like alot of fun and is well suited to tesla coils, the tune to the last ninja would sound incredible.

I built a DRSSTC about 8 years ago and have not done much with it lately until now, mostly because I could not use it at home without it annoying the neighbours.
I have however done a couple of public performances with it with great reception and have a friend who has a place I can operate it in front of visitors. I want to build something bigger with a bit more power this time.
Seems IGBTS are not only cheaper than before, but there is more to choose from.

Should I stay with CM300 series? Is there any particular part numbers that are better to go for nowdays? There are quite a few different variants in the CM300 series than I remember at the time.

Spec wise, how large a coil could I go for with CM300s? I need to dig up the specs for my coil, but at the time I think the MMC was only rated at 700 APK, possibly 800, will need to check.
I have been getting by with an 8A variac at 230V mains. Been using loneoceans UD 2.7 and have been getting streamers at least 2 metres long at full power.
Am i better going with higher rated IGBT's to make it more reliable such as CM600 and just operate at lower power?
Also looking at power requirements if I want to run 2 large coils together. Its difficult to run 2 of them if they are drawing 10A each at the wall outlet, that means I need to connect them to 2 individual outlets on a different circuit breaker.
Not sure now others are getting by when running multiple coils, do most people just turn the power down? Could I get a single variac and run 2 coils through it if the outlet can provide the power?

How does it work with SID playback?
I saw that there is a new USB MIDI interupter that can support SID playback.
I currently use the mini midi controller on my coil, can SID playback work with these?

Im currently looking for Ghosts n stuff by Deadmau5, bangrang by Skrillex and Money for nothing by dire straits.
If anyone has these tunes, that would be awsesome!