a "pot" is a potentiometer - which is what controls your volume (ie it's the thing behind the volume knob that actually changes the volume level). It does this by having a "wiper" rub against a variable resistor. If the surface between the wiper and resistor gets dirty then it can cut out. It's not unusual for a 4 year old part to have this problem. The fix is to get contact cleaner and spray it into the Pot which cleans and lubes it.