The JT6 tremolo is a Floyd Rose licensed tremolo system that is common in some Jackson and Charvel branded guitars of the late 1980s. The tremolo allows the user to change the pitch of fretted notes by pushing or pulling on the whammy bar. Over time, the JT6 can wear out and you can quickly and easily replace it with an original Floyd Rose, which are still available today, or with another JT6, which can be hard to find. The string clamp screws have a tendency to strip, so replacing the whole tremolo is often the best way to continue as JT6 parts are also hard to find.
Remove the strings from the Jackson or Charvel guitar. Unlock the nut blocks from the locking nut by inserting an Allen wrench and turning it counterclockwise on all three blocks. Loosen the tuners for each string on the head stock of the guitar and unlock the string from the bridge string clamps using the included Allen wrench.
Flip the guitar so that you can access the spring cavity. Unscrew the plate that is covering the cavity and remove the springs from the tremolo block. You can leave them there as they can be reused with the new tremolo. Unscrew the spring claw if you plan on replacing the entire spring assembly as well.
Loosen the studs near the front of the JT6 tremolo. This will allow you to remove the tremolo and replace it with an original Floyd Rose or similar tremolo. After you have loosened the two studs, slide the tremolo back enough to lift it up and out past the studs.
Place the new tremolo bridge into place where the old JT6 was located. Floyd Rose is a direct replacement for the JT6, so you can reuse the studs and springs as well. Push the tremolo forward so that the two studs are in the holes specifically machined for them. Tighten the two studs with an Allen wrench to hold the new tremolo in place.
Flip the guitar over and slide the thin ends of the springs into the tremolo block. Usually, three springs are used, one in the centre and one on each end. This will create good tension on the bridge and made dive bombs and tremolo work smooth. Screw the spring cavity plate back into place and restring the guitar. Tune it with the head stock tuners, lock the nut blocks and tune again using the fine tuners on the new tremolo bridge.