A good customer brought his new-to-him Casino in for a little work. We swapped out the tuners for Grover Sta-Tite open back tuners. The mounting holes on the back lined up, but I had to play around with the bushings. Normally with press-in bushing tuners, I keep the original bushing in the headstock and install the new tuners. The issue was that the Grover tuner posts were a hair too large to fit the bushings. So you would think that I could just swap out the original bushings for the Grover ones, right? Nope. The Grover bushings were too small to stay in the headstock so I had to remove the original bushings, ream out the inside diameter of the bushings and re-install. Ah the joys of modding import guitars: replacing metric components with mis-matched imperial unit hardware.
The player was also having feedback issues with the full hollow / P90 design of the Casino. An inexpensive fix was to stuff black foam inside the f-holes to help reduce the sensitivity of the body. Oddly enough, the foam I used was from my stash of foam that Stewmac uses to package Waverly tuners.