I bought a JTV59 used about a year ago, beautiful guitar, and I love the tone options available, but it's never played properly in tune. The high E and B are always flat at the 12th fret, and there isn't enough range on the individual saddle adjustments to bring them closer to the neck, which would be required to sharpen them up a bit.
I decided to have a closer look, so I removed the strings, and the two little set screws at the back of the bridge that adjust the bridge position against the bridge height adjustment screws. The set screw for the treble side was backed off pretty much all the way, allowing the bridge to be as close to the neck as possible. Also, I found the bridge really hard to remove unless you alternately adjust the bridge height screws slightly till the bridge stops binding on the screws.
Having removed the bridge (masking tape on the guitar body, and careful not to damage the wires under the bridge for the piezo saddles) , I could see that there is pulley shaped bearing wheel at the top of the bridge height adjustment screw, and this v grooved wheel fits inside the bridge, one at each side. The little set screw at the back of each side of the bridge determines the coarse intonation of the bridge (fine adjustment being done by the individual saddles).
Clearly the bridge height screws have been improperly positioned on this guitar, and the only way i can think of to solve this problem is :
a) relocate the bridge support ferrule(s) slightly which would be a major task, and would leave marks on the guitar.
b) machine down the little pulley at the top of the support pins. I tried this by putting the support pin in a drill and running it against an abrasive, but it barely made a mark.
Anybody else have this problem, or have any other thoughts?