I asked about an air purifier with neutral-earth near short-circuit.

Franc Zabkar wrote:

If not the cap, then maybe a leaky MOV ?

Good point, will check.

motor shorted to frame)?

I've seen a short between the neutral and earth terminals of a
refrigerator compressor. It only came to light because the owner was
using an extension cord where the active and neutral were reversed
(there was no ELCB).

Sounds the same sort of thing I've got. If it's actually a shorted
winding it'll mean changinf the motor (or scrapping the unit).

Thanks, Michael (original poster)