Intermittent 5200 controller port problem

[ubersaurus]

So, randomly my controllers will stop registering the directions right and down on the sticks. It seems to be an issue affecting at least the first two controller ports on my 4-port system; I've tested it with Mario Bros. to confirm it affects both ports simultaneously, and Adventure II has proven it affects the down direction as well when it comes up.

 

For a bit of background, I keep my 5200 unplugged when not in use. Most of the time when I plug it in the thing is working fine; I ran Gremlins the other day and it functioned perfectly. Today i went to play Berzerk, and it gave me some problems at first until I swapped controllers. Then, when I switched to Mountain King, I got about halfway through the game before it stopped registering those two directions. Tested it with Mario Bros. for both controller ports, and they worked for about a second before right crapped out again for both controllers. In the past this problem has been very obvious while trying to play through a lengthy game like Adventure II, and I tried that to be sure it was doing the same thing it did then, and yes, it was.

 

I tried unplugging and replugging in the system to no avail (though admittedly I only waited a few seconds) and have basically concluded I'm going to have to open the thing up and poke around. Does anyone here have any ideas what I should look for, or what I might have to do?

[Sonic R]

I gave my suggestions of possible trouble points on fb... hopefully zylon will see this and maybe he can help you. he is very knowledgable with troubleshooting the 5200 and may be better at offering a suggestion of what actually needs to be fixed...

 

I just fired up one of my spare 5200s and it seems to be working fine... so well that my previously dead Miner 2049er cart works in it! it will be ready for you on Friday

[fernando marrin]

open the system, on the lower right corner there's a pot , adjust a bit...

done!