Starter problem on DTC forklift

[wdbtchr]

My DTC 8606 forklift stopped cranking the other day. I thought the item under the dashboard was a starter relay and that was the problem. After checking the manual wiring diagram what I thought was a starter relay turned out to be a "starter protection package". As near as I can figure from the diagram it stops the starter from cranking if the engine has enough oil pressure to close the pressure switch. Has anyone ever seen a setup like this? I've been looking through the manual and can't find any mention of a "starter protection package" in either the service manual or the parts list. This has the Cummins 4BT engine, is this something common on them or something weird Entwhistle added? Any information or ideas welcome. I can crank the engine by jumping from the positive battery terminal to the solenoid screw, but the engine won't start, it had been working fine.

 

[wdbtchr]

I stopped my my local big truck repair shop this morning and asked about the "starter protection repair" thing and they said they never heard of such a thing. I'm thinking I may have to figure out how to eliminate it. Now if I can just figure out how to do that. I still can't get it to start jumpering the solenoid, I gotta be missing something.