I'd just get a new controller, but heres a good tactic:
I always get the year warranty from EB Games and I always trade it in for a new one near the end of the warranty, then I renew it for another year for ~$7. So I get a brand new controller every year for only ~$7. I recommend doing this since your controller will always be new and have a warranty so you wont have to worry about this type of stuff.