[Grady Clay]

The best bet is to exchange your starter for a factory Bosch rebuilt 1.5 HP starter. You get all new parts, only the housing is used.

Yes, you need to carefully inspect and repair the wiring all the way back through the system.

Yes, Terminal B is the switched power to the motor.

From my lame old memory, D is the connection from the ignition switch (yellow wire, push-on connector is 90 degrees to the wire.)

Is A a ground connection or is it a duplicate connection to the ignition switch?

Yes, you should inspect every tooth on the ring gear. You can inspect/measure flywheel/ring gear runout through the starter opening. Make sure the flywheel isn’t loose on the crankshaft.

Best,
Grady