Serial number 1A271717.......Customers truck and I am the tech working on it...should just become a boat anchor but customer wants it going,they just got it recently......

Any Crown experts out there fill me in a little on the high speed circuit of this dinosaur......from what I can make out the drive motor runs on 12 volts the when high speed kicks it it goes to 24V?
There is the A Contactor which I take to be the Line Contactor then there is B and C for high speed?(these two are to the left of the A)
The batteries are in poor shape as well as the cables just trying to decipher how this thing operates.(Volatge dosent seem to be dropping out when checking voltage at the motor...goes from 12 volts then have to push in the B and C contactors(they will stay in once pushed)...then voltage goes up to 24 volts and motor picks up speed.


The B Contactor has a switch on top that activates the coil for the C Contactor to kick it.....what is it that activates the B Contactor...the handle switches? How is the Rabbit Turtle switch involved in this?

any one have a Manual they could share for this Boat anchor????