hi i know there are so many threads on here about this but I'm just getting confused so... I've just a got second hand squire precision of a friend cheap no strings. i put the g string on to see if pick ups worked.they don't seem to. but there is low buzzing and when i touched any metal loud buzz. i checked and cleaned bridge and ground wire and its still the same. when i disconnect bridge ground the only buzz i get when i touch is the volume pot and i can just faintly get a sound through pick ups. all the wires seem secure and got a wiring diagram and they look in the right places. the amp works fine with my other bass....any ideas?