my fender musicmaster hums when plugged into my amp. when i put my finger on the 1/4 inch jack the hum almost completely goes away. when i put my finger on the strings the hum increases in volume. in attempts to fix this i have: - opened the internals up and checked for loose wiring - no help - re soldered the ground wire - no help - stuck the ground wire on the metal bridge - no help - tried different outlets - some help... i noticed the hum changes when other things in my room are turned off/on could be bad electrical in my house... i don't know. any advice? should i take the bass to a specialist? anyone know of any in central coast california?