Someone just brought round a JP 7 for me to have a look at, claiming piezo error. I setup my acoustic amp, replaced the battery in the guitar, set the mix, bass and treble to their lowest settings and had a strum. On the 7th string (B), there is an unwanted distortion, which is not on the other strings. Definitely not a good sound, making the 7th string unplayable on the piezo output. Having tried all output combinations, guitar preamp settings, checked the wiring (which looks good from the bridge, control cavity and to the preamp), I wondering if the preamp is faulty. Has anyone heard of quality control problems with the EBMM piezo preamp? My assumption is based on the fact that everything works, but the sound on the 7th string is distorted to overdrive levels, sounds like a metal zone but broken. My feeling is that there is something going on in the preamp to distort the sound. Obviously, I'd rather not have to order a replacement preamp, as the guitar is out of warranty and I'm sure they charge a lot for these things. If anyone has any experience with these preamps and would care to offer any ideas I would appreciate it. I gave the circuit board on the preamp a thorough investigation, but nothing is visibly wrong with it (wiring errors etc.). The soldering on this guitar isn't great from factory, and the tone capacitor was almost earthing against the control cavity shielding, a problem I've seen on other EBMM JP's. Although well designed, I'm not the biggest fan of these guitars, having owned 3 and worked on 2 more, although can't get enough of birdseye maple!