There are several reasons why the bridge is lifted from the guitar:

1. The guitar causes the glue to melt or dry in a hot environment, the dry glue becomes brittle and the high tension of the string breaks the seal.
2. Damage to the bracket will distort the guitar top and cause the bridge to lift.
3. A poor quality guitar may stick the bridge to the finished top, resulting in poor adhesion. Regardless of the cause of the bridge lift, you need to repair the bridge in time to avoid damage to the guitar.

Inspection:

A guitar with a lifting bridge needs to determine the nature and severity of the problem. A piece of paper pushed under the bridge reveals how much separation exists between the bridge and the guitar top. The luthier inserts a small mirror similar to that used by a dentist into the sound hole to check the internal support. A bracket that sticks to the bottom of the guitar supports the wood. Broken or loose braces weaken the top, causing the top to shift and separate from the bridge.

Re-gluing:

All guitar bridge work requires the string to be removed. In some cases, repairing a raised bridge is as simple as re--gluing it back to its original position. The bridge stays on the guitar top, reducing time and cost. Fresh glue is inserted into the gap between the guitar top and the bridge, the glue will dry, and pressure is applied to the top of the bridge to close the gap, but re--gluing is a temporary repair method. The old glue is still under the bridge to prevent the new glue from making a wood-to-wood bond...

Resetting:

To establish a more permanent connection between the guitar top and the bridge, you need to reset the bridge. The heat applied to the bridge will loosen the remaining bonds. This bridge is separated from the guitar and removes all old glue. After the contact surface was sanded to form a clean adhesive surface, the bridge glue was combined and clamped to the guitar top for 24 hours. Resetting the bridge works best because any damage is easy to see and can be repaired before the bridge is replaced.

Advanced repair:

Broken braces and damaged guitar tops require complex repairs. The lift bridge sometimes puts pressure on the guitar top and damages the wood. Broken braces require the guitar top to be removed to repair them. Repairs of this nature involve a high level of skill and should be reserved for professionals. Inexperienced people may destroy the guitar that can be repaired. At the very least, beginners should perform advanced repairs with experienced luthiers.