It isn’t as simple to just to put the power wires to the motor as you are suggesting.
it would involve work to unsolder wires and use scrap wire to reconfigure the motor to work and even then it may not function.
Your best friend is going to be able to use a multi meter to trace the voltage from one pick up rail all the way though the reverse unit to motor/field and back to the reverse and to the other pick up rail.
Otherwise as a stab in the dark you would be better off initially pulling the motor down and cleaning the armature of old carbon, carefully cleaning the ends of the brushes of any old oil/gunk and putting back together. Be careful to make sure you put back the fibre washer/shim that goes on the end of the shaft the armature end otherwise it will short out against the bearing in the brush bracket.