I was able to revive a cart by using q-tip and rubbing alcohol, but usually, it wouldn't last long. After a few play, I would need to do it again. Not sure how good is repeated uses of rubbing alcohol on the connector.
It shouldnt need repeated cleanings after that short a time. Is it just that game? Maybe the contacts are worn down on the cart.
I usually try alcohol first, then a white erasure then a pink erasure when cleaning contacts.
A lot of the problem can be due to oxidation more than just dirt. Try the NES repair cleaning paste here: http://www.nintendorepairshop.com/products/32-Nintendo-NES/81--1-Nintendo-Game-Cleaning-Kit/
This stuff works really well. I bought a Super Ghouls n Ghost that had green contacts and would not start at all. After using it, the contacts were like new and the game works great. You only need to do this once, then you can just upkeep with alcohol cleaning once in a while. It doesn't do any damage, just make sure you clean the paste off well.
QFT. This shit is AMAZING. Wish I knew what it was made of! I've used this specific website's stuff on all of my games, and they're all working perfectly.
I mean, I once wound up with a copy of Mortal Kombat 3 for Genesis that looked like it had lived underwater for a few weeks. The contacts were (as the previous poster was talking about) green, etc. It took a whole bunch of that stuff (and a little sandpaper), but it's in perfect working shape now. That's also the only cart i ever had to use any additional products on -- every single other cart I've ever cleaned with NintendoRepairShop goods has been in perfect working shape ever since. I've never had to re-clean anything so far.