Can't Quite Bring This Atari 2600 Back to Life

[Snatch1414]

So I've done basic cleaning on a 2600 Vader and cleaned out the card slot with the 'cloth over credit card and windex' method. I've gotten the system to prove it can power on but can't get the games to play. I just get random colored bars on the screen sometimes with Atari-sounding noise, or nothing at all. I've cleaned a couple of carts in particular as best as I reasonably can I think and still nothing. Some games seem to at least give me a wacked out picture like I described above while others do nothing, regardless of whether or not they're cleaned.

Do I need to maybe just try to keep cleaning the card slot, or go the extra mile and take that apart as well in order to clean it better?

Side notes: I am using the gold cable connector from Radio Shack. Also, I have two 2600s and neither's power supply seems to work. I had an old charger with the same power/wattage with a headphone-style jack so I plugged that in and it gave the system power but again no full picture.

[Hobie-wan]

I had a few particularly bad 2600 carts come my way at one point, but I managed to revive them. Since the screws are generally under the label so you can't disassemble with out damage, try this. Use flat screwdrivers or whatnot to carefully push open the shutter in the cart. Take a fairly new clean yellow/green scrubby kitchen sponge. Make it just damp enough to soft. Slide that in the gap with the scrubby side toward the pins and give it a little scrub. Not too much, then repeat on the other side. Then clean with contact cleaner/alcohol on q-tips, let it dry for a bit, and try again.

[Anapan]

Still sounds like female cart connector to me. Best Electronics has them for $4, tho replacing might be labor intensive.
Here's a Field Service manual.
A post @ AtariAge might help before you take a screwdriver to it.