How to fix an Xbox 360 controller..

My boyfriend's Xbox has just come back to us from repair, so we went out and bought Halo 3, as you do.

Got home, tried it out on multiplayer and my controller isn't working.

It's a wired one, and it seems that if you wiggle the wire, it does work for a short period of time. But seriously, aiming in a hurry, you don't really have time to wiggle the bloody wire until it decides to work.

It's the right stick that's playing up. As soon as you start the game, the screen starts to tilt up very slowly, as if you have your finger slightly on the stick, in the end you end up staring at the sky, which really makes gameplay hard.

I've tried bashing the controller (yes, I know, probably not the greatest idea, but it works..ish!) and wiggling the wire endlessly but the control is still very sticky and eventually points you upwards all the same.

Does anyone know how I can fix this? I've got the controller all in pieces at the moment, pretty sure it's a loose connection(?) but I'm not quite sure what I can do without taking all the wires out and resoldering them. And then that might not even work...

Any help would be greatly appreciated, we don't really want to end up going out to get a brand new controller if we can fix the one we've already got..