I decided the other day to pull out my old consoles and see what works and what doesn't. Found out my Mario Kart 64 is broken which fucking sucks cause that is expensive to replace but anyways.

My NES. I bought it off a friend of a friend (like $20) 4 years ago or so. Never really played it except when my brother and his family was living with us for a few weeks while they were in the process of moving. During that time I could not get it to ever work, but him (growing up with one) got every game I own to work and relatively easy at that.

Anyways my experience with it so far is I got 2 games to work (YEAH!!!) but now it is back down to 1. SMB was the first game I tried and after a few minutes of the basics (blowing in the cart, up down up down, all that jazz) I got it to work and then I put in Tetris and got it work too. Super happy at that point. But since then it has been downhill. Tried Zelda (which has always been a problem), blinking grey. SMB 2 and 3, blinking grey. TMNT Arcade, blinking grey, so on. Went back to Tetris and it was doing the same. Eventually I got SMB to work again but now I can't get anything to work besides that.

Every game (except SMB) is either blinking grey or solid grey screen. I'm not sure if there is much of a difference between these screens but at least it is consistent. Are there any known fixes for this? Is it just as simple as cleaning the pins in the system? Is that fact that one game works consistently mean that the other carts are all fucked (which would be the worst most depressing thing)?

I've also been debating on just swapping out the 72 Pin with a new one. Sounds like that solves just about every problem no matter what. As someone who has never done anything with electronics, is this that hard to do? Anyone with first hand experience in doing this with any tips as I might end up just going down this road at some point.

Cleaning everything may help, but you should go ahead and swap in a new 72 pin. The pin connectors in the front loading NES degrade rather badly over time and that's were the problems start. The job is super easy. As far as mechanical knowledge, all you really need to know is how to operate a screwdriver. There are a bunch of online guides out there, and any of them will work.

Edit: If the system is able to play some games, it's probably more of a problem with dirt, though you should put in a new pin connector anyway. If you don't have a cleaning cartridge, it's kind of hard to get to the connector without taking the system apart, and at that point you're already about a third of the way there.

More Edits: Start out by cleaning the games. Get a box of q-tips and a bottle of isopropyl alcohol, dunk a q-tip and swab the pins on the cart until they stop turning black.

@SpaceRunaway: Thanks for the tips man, I'll try and clean them over the holiday, hopefully it will fix the ones I want to play and delay then inevitable of replacing the 72 pin. I'm sure it isn't that hard but I just don't want to break it at all and half to buy a new one. Working NES consoles are starting to be hard to come by now days.