I took this one apart years ago, said "Screw It" and then just threw it in a ZipLock.
http://home.mchsi.com/~lindner24/coleco.jpg
I think usually, and in this case, the directional switches break in half.

That's the best advice...(above)
Take them all apart and use the best parts to build a couple good ones. Hopefully.
Once you take it apart you can usually find the problem visually.
Multimeters are handy too. You can get a cheap one at radio shack, get one with a continuity tester. (It Beeps when current flows)