Peavey,
it could be the field's in the motor but there are other things to consider as well that are part of the field circuits.
- FU8 which is the 150A B+ field wiring motor circuit fuse located on the contactor panel.
- cables from field windings to field wiring assy
- field wiring assy to H-bridge Control Module (HCM)
- HCM to vehicle manager
- field wiring assy T1 - T4 (base leads for TM1 and TM2)
- TM1 or TM2 may be bad
- HCM may be bad
- VM (vehicle manager) may be bad
- drive motor may have open circuit in windings

YOU WILL need the service manual for the correct procedures and test points to correctly diagnose and test these circuits and components.