Is a stepper making a hissing/sizzling noise after being run for an hour or so a bad sign?


I noticed it the other week after doing a longer run than normal of parts on the lathe, but all was quiet again the next time few times I used it. However I done another longer run this week and the noise returned. The motor is always cool to touch, so it's not like it's overheating.


It is an old round stepper, which I'm hoping will last another few months until I get a lathe replacement sorted, but should I be looking to change the motor soon?