Atari 2600jr with color problems?

Today during a cleanup I spotted my "collection" of Atari 2600jr consoles. They usually go very cheap on flea markets here so from time to time i pick up one as a spare (which regularly ends up forgotten inside a wardrobe). Beside cleaning them and putting them away again I decided it would be a good idea to test them as some were never checked for anything but basic functionality.

Most of them were fine, but one showed a weird behavior with graphics: distorted colors. Lucky me, it was easy to fix. Keep reading if you want to know more!

The defective one was suffering from a very bright and greenish picture (switching to B&W for a few seconds at random too).

Poleposition working fine on the left, on the "bad" 2600 on the right

At first I thought the TIA (the chip producing the picture) was damaged, but then it came back to my mind that inside the 2600jr (no idea about other models) there is an adjustable potentiometer used for color correction...

Here are some pics of the partially disassembled console:

The interesting pot is on the left... can you spot it?

Here it is, on the left of the first switch

Regulating this fixed the picture! If You have the same problem You can try to turn it while the console is on and the picture is on screen. Just use caution, a plastic screwdriver (so You don't short anything if the thing falls from your hands) and patience. I take no responsibility if You damage something (or Yourself) while doing this!

By the way, there was an interesting talk at the last 28c3 congress about the Atari 2600 platform, here is a link to the HQ version.