I have just recently fixed my old Nintendo Entertainment System and its working like new again. All it needed was a new 72 pin connector. However sometimes you still have to put in and take out the cartridge, and periodically I have to blow on it. But what do you expect from an old system that was from 1985. Overall though it works great and I feel like a kid again.
Here is a video of me fixing the NES with my dad (I know that some people might say that you can just tighten the pins. But trust me my friends that still have NES's too said to get a new one).