Thanks for the repies:
Bohoki- good suggestion, River Raid is good for testing the keypad. In fact, I used River Raid to test out the controller in the second port. As I suspected, the number inputs work correctly in the other port. Its too bad that you cant just play games as player 1 in the second port. I heard you could do that on the intellivision.
The most sophisticated repair i have ever performed is fixing jittery Atari 2600 paddles by disassembling and cleaning the contacts. I have never soldered and don't own a soldering iron. But it seems be a big plus to be handy at repairs if you own a 5200.
The way Zylon described it makes it sound like it is a pretty straightforward repair. Just open up the casing access the ports and solder the pins so they are straighted out?
However what confused me was if the pins were bad, wouldnt they just not fire? Why would they output the opposite number accross the keypad? does anyone know what that would indicate and if soldering would help that?
I wonder if i should just try to secure a new cheap 5200 on ebay from someone who has given up on it because their controllers dont work