I just got an acoustic Washburn as a gift (AB-20) and hooked it up to an amp. The A & D strings are picked-up fine but the E is hardly picked-up and the G string is almost completely un picked-up. Is there something I can adjust or fix? I've already twiddled with everything and have no clue. It has a built-in battery tester but I'm gonna throw a new one in there anyways. I just want to play!!!!!