> Just rip your NES apart, clean everything, and I mean everything. You'll be
> amazed at how much crap can build up on an NES mobo after 10 years. Same thing
> happend to me and it still fucks up the odd time, my suggestion is to take off
> that little metal bar where the game goes, and stick another cart over top of
> the one that's loaded, or get yourself an NES game genie.
THATS what kills most of those front-loading NES units.
The angle that the game genies needs to be shoved in at, actually bends the cart contacts inside up at a slight angle, so that when you use it with a regular cart, in the regular way, it doesn't make good contact.
My suggestion: if you are going to use a game genie, leave it plugged into the unit, and plug the carts into that (if you can). Otherwise, reserve a single unit for use with the game genie, and keep another "good" NES unit around for non-game-genie usage.
That being said, I have a front-loading original unit (serial number 33-thousand-something), never had a game genie in it, and still going strong. (Although it does sometimes need another cart plugged into the top above the real cart to make good contact. Maybe I should clean it.)