--- #4 Martian 
Dokk, disassemble it and layout the bits... so we can get a better look.
Does it pivot at the rivets?
The WB is adjustable... no?
The center alum upright on the rear chassis section looks bent toward the rear. Is it?
The 'W' shaped spring maintains the ride height.
The single spring steel in the center controls the 'bite' and possible 'changes' the ride hight/spring rate at the same time. If it touches the brass guide post spring then the guide post may have had a 'coil' spring floating action.
Looks like a... post FT16D era chassis to me. If EBD only to mount to the missing motor bracket. Without the bracket???
Those are all guesses " I know nothing", Mr. Prez. 
Jairus, on 07 Jun 2013 - 10:48 PM, said:
The insulated screws are interesting. Makes me wonder if they were planning on a wireless transfer of power from the guide to motor.
Good point!