So, I am in the market for a sub-200 commercial grade used grinder, which seems to be a rare but still extant breed. I came upon a La San Marco SM 90 in as-is condition, that would cost me $75 shipped (already bargained down from $125). The caveat is that it doesn't work. The owner initially described it as "Motor starts up and spins but stops spinning after a few seconds. May be an easy fix but I'm no mechanic" so I asked him for a video of it, to which he sent and said that it wouldn't start at all this morning. In the video, I hear the motor spinning but the lower burr doesn't move.

So I was thinking it might be a shear pin or something, but based on this thread from 2016 (Possible causes for lower burr not moving) there doesn't seem to be anything of that nature on the machine. Unless there is and it's just not in the diagrams. Does anyone know something about the construction of this grinder's drive shaft? Any ideas what this could be and if it's an easy fix or not? Is it a good buy for the price? I'm willing to take some risk but I'd like a good 70% chance it's fixable before I spend $75 on it. Any other thoughts on the grinder are welcome!