Maybe its time you replaced the volume potentiometer!
"What?" I hear you say!
It isn't as tricky as it sounds - The Potentiometer, or Pot for short, is a really simple device that feeds the curent from the pickups to the amp. they become scratchy and intermittant with age and so by replacing them you can get your guitar sounding as good as new.
We stock all kinds of volume pots for electric guitars , including tone controls and push pull pots too!