I have'nt looked at the parts fiche but I would start at the pickup. It's either cable driven or sensor driven.
If its a sensor you can test it w/ an Ohm meter, and you should see resistance. I don't know the number but if its 0 then your on the right track. If it is cable driven that cable should pull out in one piece, and have a square box shape on both ends. If not it snapped.
I hope this helps get you started, until someone else has an idea.