Try contacting Mamiya service dept, they can supply you with an exploded view diagram of the camera and may have a service manual as well. I dn't have a contact person on hand but form past experiance with them, they are very accomodating.

I'll try asking around for one as well, perhaps someone has one in their basement.

Mamiya contact....
http://www.mamiya-usa.com/customer-s...ct-mamiya.html



Hope this helps...