Tune-o-matic bridge as found on Gibson and other guitars was designed by Ted McCarty and introduced in the mid 1950s as the ABR-1. The design was updated by Schaller in the 1970s and the new bridge being termed the “Nashville” bridge by players as its introduction coincided with the Gibson factory’s move from Kalamazoo to Nashville.
These bridges do suffer from one problem – they can collapse under string tension. This makes achieving a consistent string height across the fretboard impossible and can cause the inner strings to buzz.
The image below shows the problem.
Fortunately this problem can be fixed by gently bending the bridge back using a vice. If this is done carefully and slowly the bridge can be re-straightened as shown below:
If the bridge has been previously bent and straightened however, metal fatigue can cause the bridge to crack and then there is no alternative but to fir a replacement.