I'm sure you're all excited about the work today...here's what happened. I watched the Washington Huskies (#5 - 6-0) get beat today. Now 6-1. Oh well.
What happened was after the game I clambered underneath with a new digital meter that was delivered today and found 12 volt on one big supply wire. Soaked all the local connections with P-B Blaster. Disconnected the 12 volt wire and covered the end with a sock after using a rotary brass wire brush to clean up it's terminal. Did the same to most of the other connections under there, including removing 2 inline 20 amp fuses and polishing their terminals. Liberally applied contact spray and the wire brush treatment where ever I could.
Decided that all the terminals and wires going into those terminals were in good shape. Did have a bit of crud here and there, but nothing terrible. Also did the 'tug' test of around 20 lbs on wire terminals with no failures.

You can see that the copper terminals are in good shape.
Here I've gotten the terminals all polished up (and it didn't take much) just before reinstalling them.

After all that and more, went inside and...no operation. Hmmm. And it's in the 80's by now.
So went back down, found the ground lug, and used P-B Blaster on it. Thirty minutes later, tried unsuccessfully to remove the main nut. On there good. I'd need an impact driver for that one. But I did reef on it a bit and tugged on all the wires. Everything seemed solid. When I went back inside, now the motor runs when the switch is pressed.
Tomorrow morning, when it's cold again, I'll test it again.
My new meter has a Bluetooth feature so if I can get that working, I'll be able to monitor the voltage reading inside when I press the extend button. Magic.