It looke to me like there was once a bolt head right in the center of the thing, as you look down the into the hole. Looks like the bolt head has snapped off because the shaft of the bolt spins as the motor runs, but the shaft isn't connected to anything (anymore).
The head of the bolt must be down in the trap now, or maybe just snugly off in a corner somewhere.
The motor spins at the usual speed, but it doesn't turn anything except the shaft.
The "cutting assembly" moves freely, by hand, around the shaft, and even moves up and down, off the shaft, so nothing is stuck.
In a perfect world, it seems I could just take the old Disposall out, take it to a machine shop where they could extract the headless bolt, then just buy a new bolt, reassemble the thing, replace it in the sink and then have a cold beer and relish a job well done.
I'm trying to avoid spending a fortune having a plumber come in and fix / replace it.
Am I right about the bolt?
I called the GE answer center 800 number and the guy was pleasant but said he couldn't help me without a model number !! (even though I told him it was probably a 1985 or 1986 )
I might end up buying a new insinkerator, but I still want to know if I'm right about the bolt theory.