Tech: Wurlitzer 3700 Gripper Arm Problem

I've got a Worlitzer 3700 Americana that was working just fine! We
moved it to another house and now it has a problem. It mechancially
functions perfectly except that at the end of play the gripper arm
stops at the top of the cycle after picking up the record. It
happened when I first got it and I just nudged it a little and it
completed the cycle and returned the record to the carousel. I've
never really gotten into the mechanical mechanisms of this machine. I
have a manual - where do I start with trouble shooting this?

Thanks,
Tom