Readout flickers with motor running (glass scales)

[MidniteMachinist]

Yeah, it's a mechanical issue. No idea how old the belt is, but the machine definitely sat unused long enough before I bought it, that the belt took on an oval set. I could feel it when I turned the grinding wheel by hand, and it was causing ripples in the finish when I started grinding in the mag chuck. The belt was going to be the next thing I replaced after I got the scales installed and working...

Took the belt off, fired up the motor, and the display is rock solid. Ordering a new belt asap.

Thanks for all the help, peoples. Especially Yuriy... Thanks for doing so much testing on your own, to help me solve this. Would've taken me a lot more time and frustration to figure out, without all the input.