Thanks for the insight Terry. The heat was noticeable along with the odor of hot oil when I opened up the rear door last night. I’d certainly say that the motors were well above “quite warm.” This was probably the first time I got into the back after the machine had been used for such an extended period. Other times that I have gone in the back (for troubleshooting various issues), the motors had likely only been working for a short bit and they were more like what you described (i.e., warm but not hot).
The motors don’t seem noisy to me (not anything more really than a quiet hum), but I don’t have lots of familiarity with bingo machines and so they could be louder than they should be. I added several tsps of oil (blue 3in1 stuff) to the gearboxes when I picked up the machine about 1.5 years ago, but perhaps they could use more. Will check on this.
Also, I haven’t taken apart and cleaned the control or mixer units and so it’s possible that the motors are under some strain due to grimy/gummed up conditions. The machine had been sitting for some time when I picked it up and had some gummed up steppers and added wiring hacks to it. Given that the mixer and control units seemed to be working properly, it was one thing I thought I could put off. I suppose the temperature issue may now be a good reason to stop putting this off.