You certainly want to make sure all of the internal connections are solid. But it sounds more like a bad volume knob to me. It's called a "potentiometer" which is basically a variable resistor. You can try some contact cleaner in the pots, or just try replacing them.
If you replace them, you can order it direct from the manufacturer or perhaps your local music store can help you.
Thank you for your indulgence,
members.dslextreme.com/users/basscliff-www.kellyraeband.com-www.thebuckaroostrangers.com, Country Bassist #72, Fender Bassman #99, Carvin #300, GK# 1017, P&W #1305
Last edited by BassCliff : 07-25-2013 at 04:55 PM.