Problem with NIB 22975 TMCC Culvert Unloader

I think I recall reading that the vintage (non-command) versions of this accessory were fussy about string tension, clean pulleys, etc.  Whether the motors are controlled by radio waves or a push-button, it sounds like some of the old gremlins hung around.  I have one of these on my shopping list too, so I hope you get it working reliably.  Following!!

Since this thing sat on the shelf for 20 or so years (I got it in its unopened original shipping container), there’s a possibility that something is no longer pliable enough, or perhaps needs some lubing.  I’ll be checking it out later today.

If you open up the grapper that lowers and raises the magnet assembly, be really careful re-assembling it. The gears must be timed perfectly. Just one gear tooth off and it will not function correctly. This may take some experimenting to get the gears in correct order.

Thanks for the very helpful comment @Chuck Sartor.  Luckily I haven't started on it yet, but will do so in about 10 minutes.  I'll be taking plenty of pictures to help my failing memory.

Fixed it!!!!  It wasn't difficult, just time consuming (mainly going through the learning curve) and luckily didn't require electronic repairs, only adjustments.

I guess somehow the thread in the pulley system unwound once or twice from the spool which caused my initial problem.  To fix that you have to take the cover off the pulley housing to expose the spool (pink).  I then had to remove the cover of the motor housing (blue), there were 3 screws, 2 behind it and one just to the right of the spool.  That releases the main motor in the back as well, but there was no need to go into that part.  I then manually turned the spool socket from the back so that the pulley was fully retracted in the housing (green).  After all that, the lift mechanism wasn't moving very good along the rails.  The motor (blue) is what moves it back and forth.  There's essentially a traction tire that moves it along the rail, so make sure the rail is clean of any dirt and grease.  I also had to finely tune a little switch (yellow) that stops the movement along the rail.  The switch over the gondola car wasn't being activated when the crane was over it, so I had to adjust it.  Finally, when the crane brought the pipe into the drop off area, the gate (white) wasn't opening fully.  I had to move it by hand quite a few times to get it broken in, along with adding some oil in the the bottom slow of the gate.

It now works properly.  I even added a little person, with a yellow hard hat, on the side to control the operations.