You know that there were only 300 of the 5FX made. They were originally model 5A's with 1 humbucker they add (Charvel) the single later. the early one had no tone knob.
Looking at your guitar the neck needs to be moved to the right (treble side) it's not inline .You have the low E string off the fret board near the body. This is the problem with your guitar!
This has always been a problem on badass bridges they are not thick enough to seat solidly on the post. Shaller bridges are thicker and fit tightly on the post as do most newer stop type bridges.
No one I know buys Kahlers that why they went belly up in the 80's. I must admit I have one guitar with a Kahler on just to remind me not to ever buy a guitar with one on it again.