Hi all,

So I have this bench grinder (one of the ones with two wheels of
differing coarseness on either end of a spindle, the motor being in
the middle). Anyway, it packed up one day. Wouldn't spin by itself
even with a prod; just made a humming noise. I suspected a duff
capacitor which turned out to be correct. This grinder uses a 450V
2.5uF one and finding a spare online turned out to be simple enough,
if not all that cheap at a fiver. Swapped out the duff cap for the new
one and it worked fine again. Then today it packed up again, same
failure mode as before. I whipped the bottom off and checked the new
cap expecting it to have gone phut but it was fine, much to my
surprise. So I'm stumped. I can't see any other caps in evidence,
either.
Any idea what's going on here?