Well, it looks like my old Lortone slab saw is down again. By the time I can afford a new one, I will have taken this one apart so many times I'll be able to build one!
This time it looks like the drive motor has gone bad. I have no idea what it will cost to replace it. I'm going to take it apart tomorrow in the daylight--I can think of one thing that might be wrong that I can fix--the Allen screw on the shaft may have worked loose. If that's not it, then it's a new motor.
It's a good thing I'm handy with tools!