Hi everyone ---
I used my birthday money this year to buy a 2600 Vader with a few games. No joystick came with it, so I purchased an original joystick from a different seller on ebay, who assured me the joystick had been tested and was in good working order. When I had received everything, I giddily (with flashbacks of childhood) hooked everything up and the first game I played was Space Invaders. It wasn't until I tried another game that required "up" and "down" motions that I realized my "up" didn't work on my joystick.... so I purchased another joystick. This time I bought a brand new joystick that is a replica made to work on the 2600 and some other systems. It looks almost identical to the original. It never occurred to me that this could be a problem on the console... until I tried the second joystick and got the exact same result. Everything on it worked fine except I can't go "up".
I have never taken a system apart -- I am not mechanical at all and probably don't have the tools for it. I am willing to try small things that won't likely end in disaster if anyone has any suggestions.
Also, if anyone repairs systems for a reasonable fee I would be more than happy to talk to you! I really want this baby to work! 
LL