Does anyone know how to replace, or at least remove for inspection, the 'speed selector assembly'? I cannot adjust the speed, the handle won't pull back and forth. I suspect that it has gear teeth on it that moves the top pulley head back and forth and the the gear teeth are stripped - or out of position on one or the other. But I cannot figure out how this assembly is removed. There is a round plate that screws to the lathe headstock and I have removed the 2 screws but that plate will now move a little (spinning), it shows no inclination to pull out from the headstock. Anyone have any ideas?