Because of the possibility that placing the heater near the hydraulic assembly could have been a coincidence, today, preparing for tomorrows departure, I didn't set up the heater. But I was prepared too.
It's important for my schedule that I leave tomorrow, and it's been getting down to the teens the last two nights. So at 11 this morning, I started testing the slides. I could get no movement from them even as the air temps progressed to 60F.
Finally, since it was 4 pm and the temps would soon fall again, I took my rubber mallet and focused a blow to the back of the small motor on the assembly. Immediately went inside to test.
And the slides were working. So when I'm in an area where it's warm and I can work on the problem, I'm planning on removing that motor, and the nearby solenoid, and digging into their innards to see what I can see. Probably be able to do that next Tuesday as I'll be in the Phoenix valley. Should be warm enough for work.
I like Don's test idea, but today sort of proved it's a motor or solenoid issue in a very small area and I think I know which component.