http://www.fretnotguitarrepair.com/ElectronicsRepair.htm
Is quite good - before changing the Volume control consider a cleaning spray - I used to use Sevisol and this site above suggests DeOxit - any hobby electronics shop will have an equivalent. Just a little spray and twiddle the control for several turns back and forth.
If you can manage a soldering iron a switch replacement is easy or if you're not confident then offer beer money to a friend who knows how...
Good luck...
Peccavi
July 2009