I recently installed a set of jazz basslines quarterpounds into my sx jazz bass. i had them done by my local music store. the only prob is there is a hum noise i know i will most likely always have but i think there is a ground or earth prob with the bass cause when i touch any metal part the hum noise is not as bad. i have brought the bass back to the store and he told me theres nothing can be done which is very annoying. Am i been told the truth here? or is it a bad job done by the store. i know u can get rid of the buzz when u touch liike strings/bridge and that so he must be just giving me the run around i guess. any suggestions here would be most helpful thanks.