Make sure the opto interruptor is lined up properly with the optos. Test each of the 4 optos is working in switch test. Make sure the interruptor is lined up on the shaft properly (you can see this in trunk test and the DMD will show which side of the trunk should be facing front).

Could also be the dual motor drive board. I had an optointerruptor just go bad in mine, causing the trunk to always be spinning in one direction. I documented the fix here -https://pinside.com/pinball/forum/topic/tom-trunk-dc-motor-control-board-issues-a-16120

The same board is in your MB. Swap em out and test.

If it's the board/optointerruptor I'll gladly fix it at no cost.

Should it spin endlessly? When my opto interruptor went bad it was turning one way constantly but it can only rotate 270 degrees due to the cotter pin stuck in the shaft. Check that... As for the push/speed, perhaps the gears are starting to strip? How did the gearbox look when you regreased it?

Otherwise your symptoms sound super weird and erratic. If you haven't already, I'd try reset to factory defaults on the ROM, I've heard of other weird issues being fixed this way.

You shouldn't be able to move the interruptor. Hoping you got the metal one. Either way, the set screw should be screwed into the dimple in the trunk shaft so it's properly aligned.

Good info. On that last video, you're in a mode so the trunk won't turn.

Very weird. I'd make sure your CPU>driver board ribbon cables are secured, worth trying swapping it with another one.

Any luck on the factory reset? Get the 1.4H ROM if you can.

It seems that the trunk only rotates clockwise (top perspective), is this true? Same results with the other motor control board? How it keeps going on it's own HEAVILY makes me suspect the motor board. Especially because the switches all trigger, but the trunk keeps moving. Mine also had a leaky cap. Motor board look OK? Any corrosion on any parts?