A fender Hotrod deluxe 3 stopped by with its owner who was fed up with it humming loudly. Humming badly with even the PI removed....hope it's not the OT !. New power tubes did nothing so I checked the bias...what bias !!..zilch. Remove power tubes and recheck bias...bias MIA. Thought I may have to chase down a faulty component in the bias circuit but my gut told me to check the power supply filter caps. Yep the B+ filter cap was stuffed...a new cap and... silence...no hum , no hiss , good tone and yes we have bias again. Hopefully this may save someone else some time.