SG9120B - only goes west

[pacificrim]

I put away a working SG9120B 2 years ago and today tested it. It only goes west, both by receiver or by the button. Pressing East results in a red light and a click - same as with the receiver.
I opened it up and applied 12v power to the motor board - correct polarity moved it east, reverse polarity moved it west successfully.
Any ideas?

 

[Cham]

Check for corrosion around the switching circuit and relays. Had a similar problem with a different motor a while back, had to re-solder some of the joints and I think I replaced some caps and a resistor or two... Some moisture had accumulated on the circuit board.

 

[FTA4PA]

Here is a thread about that motor that may helpful. Something is mentioned about the function of the limit switches and there is a link to a tear down and rebuild: http://www.satelliteguys.us/xen/posts/3007945/