If the turret pops out, and doesn't rotate, probably the unclamp switch. If it rotates then goes back but times out, it could be the clamp switch. You really need to check the I/O signals and see whats not right. If the machine sat for a long time, my guess is it's a clamp switch not popping out with the turret. A little WD40 works well. Those early machines do eat Bestac Boards, which is a small relay card. They are pretty cheap.