Roadmaster passenger power recline is stuck (bad drive cables?)

I finally got the front seats out of my 92 Roadmaster wagon. The passenger seat has been stuck in full recline since I got it; when you try the switch, you hear the motor start and then immediately stop.

Once I got it off I saw what I'm guessing is an aftermarket motor installed (the others are original). This is what it looks like down there:



When I detached the drive cables, I saw that the motor actually spins:



The video doesn't show it very well, but the cables go in and out as they're spinning. The ends of both cables look rounded off, especially the one on the left (helpfully shown on the right of this image):



Is that my problem? If so, what do I need to do to fix it? Thanks.

That may be your problem, but they look long enough to engage the square drive hole in the gearbox. Check to see if the jackshaft gearboxes can be turned. I had the gearboxes freeze on mine. The grease gets hard as it gets older. If they are stuck, you can try to clean and grease the gearboxes, and clean the jackscrews of rust, or you must replace the entire jackshaft assembly. If the jackscrews are rusty, that may be the issue. The jackshafts are synchronized for length, and if you move only one it will bind. They are held on at the back by a push nut on a pin, and at the front by two Allen screws, that also act as a pivot. If you remove both of them at the same time, the seat will flop around. I managed to get the push nut off without destroying it, and used it over again to install that end. I removed the Allen screws first, because the unit could not turn with the screw. I had to pull the seat cover back for access to the fasteners.

Make sure the jackshafts are protruding the same amount when you put it back together, or it will bind.

If only one is turning it will bind, and the motor will internally throw a breaker, or the breaker in the fuse block will activate.