In my fender P, I have one of those raven lab preamps inside the bass. When I bought it, it was used and I have no idea how this piece of equipment works. Recently my bass with the preamp in it has just somewhat stopped working. When I first plug in it works for about 30 secs of playing then just makes a very soft fuzzing sound. Is this the normal symptoms of needing new batteries or is this another problem all together? And if I do need new batteries, whats the best way to get at this preamp?