I need help identifying a used machine I am interested in purchasing. The owner tells me it is an original Mark V from the early 80's. He didn't know model 500 or 510 etc and I couldn't find any serial numbers on the headstock. The unit comes with the smaller table and only one extension table which suggests to me that it is a model 500. My confusion is this: the headstock has the large red "safety" switch to power on the unit, not the simple on off toggle I see on images of older headstocks. This leads me to suspect that it is a newer model 510 headstock, maybe even a newer 1991 "C" headstock? The owner also had two different fences, one of them having the top T-slot indicative of a model 510. I am thinking the headstock is not original to the machine. He also has the current miter gauge with the squeeze stock gripper which I thought only came with post 1985 machines?
Any help is appreciated!