probably slowly getting damp in past the shaft seals. It is not going to trip any RCD or do anything nasty at 1M ohm, but the fact it is getting worse is not a good sign - I'd suggest it can stay in service for now but the users should arrange to have a spare to hand, as one day it will probably go off and stay off !
Presumably when it fails it is not a repairable unit, so there is no option to have it serviced early.
probably slowly getting damp in past the shaft seals. It is not going to trip any RCD or do anything nasty at 1M ohm, but the fact it is getting worse is not a good sign - I'd suggest it can stay in service for now but the users should arrange to have a spare to hand, as one day it will probably go off and stay off !
Presumably when it fails it is not a repairable unit, so there is no option to have it serviced early.