Hello!
Dont know if its any help to you but on my BG 3000 (tangential) the raising middle adaptor got halfway stuck which resulted the pickup to lower just millimeters off the aluminum platter when I was trying to play a single! However after taking out the hole platter and the midlle mecanism carefully cleaning the plastic tube which goes up&down the platter size detector works again.If you have same size detector, my tip is to clean it well also, the center needs to move up/down with ease or you will get probs.