Unwrapped the X2 cap , 1.7m long with a meandering 80 percent continuous
spark errosion line along the length averaging to the middle but no obvious
burnt or melted patches. Whether thousands of instantaneous discharges would
trip out an MCB or imbalance RCCD/ELCB/ GFCI , no idea.

Owner had removed the cover and extracted a load of fluff from inside the
minor fan air path. 4 of the 6 close pasked emitter Rs had faded printing
plus the changed value Zobell , perhaps them seriously overheating was
causing the electrical smoke smell. Change the X2 and Zobell and externally
cleanable filter cloth going over the minor fan.
the main fan you can shine a torch through front to back to check for any
blockage

The mains Tx nut was loose but no smoke trails inside other than black
soft-plastic plasticiser, from the disc pads, leeching and brown staining of
2 bits of sticky tape that hold the white high temp covering tape winding in
place.