Atari 2600A problem

[Hateshinai]

I bought an Atari 2600a (the one with 4 lever switches) and I am having some problems. It powers up fine, the joysticks work and the sound is fine. The problem is the video output. The picture seems glitchy: sprites appear twice on the screen, there is garbled graphics, the aliens in Space Invaders are HUGE , some sprites do not appear at all. Also some games seem to crash, for example in "Pac-Man" pac-Man keeps dying as soon as the game starts. I have 15 games and they are all problematic. The one that works best is Pole Position and even in that there is an extra line of garbled graphics in the middle. Also, the glitches vary from game to game but are always the same for each title (even for different copies of the same game). I cleaned the contacts of some games with no result. I opened up the console and it was REALLY clean inside but I can not reach the cartridge contacts on the console (the thing is shielded like freaking Fort Knox).
Any ideas?

edit: I can't spell worth crap

[vash23n]

I bought an Atari 2600a (the one with 4 lever switches) and I am having some problems. It powers up fine, the joysticks work and the sound is fine. The problem is the video output. The picture seems glitchy: sprites appear twice on the screen, there is garbled graphics, the aliens in Space Invaders are HUGE , some sprites do not appear at all. Also some games seem to crash, for example in "Pac-Man" pac-Man keeps dying as soon as the game starts. I have 15 games and they are all problematic. The one that works best is Pole Position and even in that there is an extra line of garbled graphics in the middle. Also, the glitches vary from game to game but are always the same for each title (even for different copies of the same game). I cleaned the contacts of some games with no result. I opened up the console and it was REALLY clean inside but I can not reach the cartridge contacts on the console (the thing is shielded like freaking Fort Knox).
Any ideas?

edit: I can't spell worth crap

Are you using the original RF output that came with the console? I had endless problems with 2 of the 2600A systems and thought it was the system at first, but it turned out that the outputs are usually just not up to par anymore. I sent it to the Longhorn engineer and he installed an A/V kit that allows hookup through your typical red, white, and yellow cables. Works flawless now. If you know your stuff about modding, the kits are available for self installation as well. Here is the link:
http://www.longhornengineer.com/Main/HomePage
I assume you are having the same problems I had, but I guess you never know. Maybe some others on here can give you a way to do a diagnostic check to see if it could be something else before you spend money for nothing.

[Hateshinai]

I am not sure that the AV mod will solve the problem - it still does not explain why some games keep crashing. Also, even the parts cost more than what I paid for the whole bundle. I am definitely not going to play the games for any prolonged period f time but I would still like to get the console working adequately, for completeness sake.

[Majors]

The A/V mod is not too hard if you just want composite. Don't have the site, but you have the same internet as I do. I had to add a rheostat to be able to adjust the video signal since I noticed the output does not always work the same on different TV's.