Writing about the Nintendo Entertainment System's birthday a couple of weeks ago put me in the mood for some retro gaming. I didn't want to dive into the legal grey area that is emulation—my fever can only be cured by the real thing. I wanted to play the original games with the original controllers, so I hopped on eBay and snapped up a few used cartridges to expand my childhood game collection.

What I quickly found is that different vintage game vendors have pretty drastically different ideas of what "cleaned and tested" means. I've bought "cleaned and tested" games with connectors caked in dust, coated in tarnish, and (once) partially obscured by a dried up old spider carcass.

Putting dirty games in your console is bad for it, and a dirty console can go on to infect the clean games in your collection. Luckily, with the right tools and an assortment of chemicals, getting these games back into near-new condition is no trouble at all. Here's what you need.