I've got a pre-EB ('77) stingray which while playable, has an odd behaviour with the bass/treble knobs. The treble has relatively little effect, but the bass when rolled off actually cuts out everything but the highest frequencies. I haven't had a chance to capture an exact frequency curve, but that doesn't sound right. Has anyone seen this, or is it in any way a common problem? I'm suspicious of an out-of-spec cap that would have been part of the frequency circuit.