For me, Not CSI, but like olden days assisting with “Root Cause & Fault Tree Analysis”
When I suggested fingering the switches and noticing the voltage go away, that was measuring the yellow wire with respect to the “black” wire. The way I read your reply, I assume you took your voltage measurements with respect to chassis ground.
When I had to quite work, I tried consulting via phone/email BUT I got too confused (like now).
But if I got the conditions correct, I think your results actually do show the closed limit switch is NOT opening and has the motor in locked rotor in the closing direction.
To continue to trouble shoot for a “hot motor”, thinking it is due to incorrect power,
could you make a 12VDC light that could be plugged in instead of the motor.
Are you able to raise and lower the buckets, by hand?
I think, we should be able to say the relay and wiring has the motor going in the right direction when lights are cut on/off. Thinking then the problem is the power is still being applied to run the motor. The light bulb will show that the path to ground is being opened by the limit switches when the buckets are at the correct position
IF, the switches are working correct AND your motor is getting hot due to electrical, then the internal winding insulation may be bad.
Using the OHM setting on your DVM may show the problem, just measure each of the terminals wrt chassis ground. If it shows any resistance, then current will make the motor hot without it spinning.
I said may, because some DVMs don’t have the capability to check the quality of motor insulation.