Here's one of my Gotoh
GB9s. I was able to disassemble and reverse it.
As I understand it, the GB640 Res-O-Lites are just a lightweight version of the GB9
( which is itself lighter than the stock Fender reverse tuners ). So, unless there's some
design difference, you should be fine.
Nicest thing about these tuners is how smooth and effortless they operate.
