I think you still have a motor field problem. Have you Megged the Field Coils, and Brush rigging?
Agree, that I think there may still be an issue with the motor fields, or at least some genny fields(the burning out of a motor field may have taken out others in the circuit). Have you another lift that is working to measure fields? I would check the ohms of each motor field coil disconnected( it may be unbalanced), plus the intercoils, and do the same with shunt field of the generator. The print is a little hard to see, but the GSEF( I think- above the armature loop circuit) I would check, plus the direction field(cant see what its called) on the left hand side, but should be the generator shunt field. Check for ohms, shorts to earth, for balance between up and down etc. Adjust the neutral plane to the mark on the generator and you shouldn't have to move this. Any way let us know how you go.
