Recently I purchased a used Ibanez BTB7, cosmetically in great shape. There seems to be an issue with the treble pot..... Even with the treble pot turned completely off, there is still quite an abrasive amount of sharp treble bite. I don't think it's the preamp because it's still that way in passive mode too. I opened it up and didn't see any kind of trim pot or any thing to back off on the highs. When rolling the treble pot forward it does change the tone to (yikes!) even more treble, but I don't think it's functioning properly...I just can't believe you're not supposed to be able to roll the treble all the way off on an instrument this nice.... any suggestions short of taking it in to a tech?