Alternatively, if you're really, really brave, you could do what I did: disassemble the NES down to the header, and use a small screwdriver to bend the pins slightly back into position.

However, it is easy to bend them too far, and increase the insertion force required to actually load the game. Or worse, snap off one of the contacts.

I did this with an NES that I purchased for $5 off eBay (over 10 years ago), and have had no problems since. I believe this was a year or two before the 72-pin replacement was widely available.

That's not really being brave ; I mean, it's not dangerous. The NES is very serviceable.

I guess I forgot to mention that you have to play Mumblety-peg after bending each pin.

Killing the lock-out chip is a bit more risky, but also works wonders:

http://kyorune.com/modding/article.php?id=26

I have done this and can confirm it was really easy to do the fix. It works, but it should be noted that if you leave your cartridges pushed down in the system all the time it will just wear out quickly again. The design is just flawed.

I have done this and it works wonderfully. It is very easy to do as well.