Due to "circumstances" I haven't had the opportunity to use my lathe since about 2018. Of course when I went to use it yesterday the VFD was randomly tripping the RCD. The RCD is right above the lathe so I put up with it for a while, then decided it was time to pop the lid off the VFD. I snuck a look under the logic card to the power board to see 4 RIFA caps smiling back at me.
Today I popped the logic board off and saw them in their full glory. I put a meter in series with the earth line and saw it started at about 2mA leakage, and gradualy climbed to ~10mA when I gave up. I decided as they were Y caps and supposed to "safely fail open", I'd cheat a little bit. As Big Clive would say "naughty". So I clipped the earth pin on the VFD to the Neutral through the milliameter and came inside to wait. The VFD sits in my Granny Flat at the back of the yard. About 15 minutes later I heard a loud "pop" and thought, that'll be it.
I was greeted with the culprit in its full glory, opened like a kernel of popcorn. Probably not the most kosher way of identifying the faulty device, but did the job. Of course it's going to take some time to get the smell out of the place.
Of course the pads are under the IGBT pack, so that had to come out. Lots of use of the desoldering gun and half a roll of wick later (and a bit of swearing) and it's ready for a Digikey order and some new caps.