At some point, you may want to replace the tuners on your guitar. Maybe the original tuners slip, maybe they are broken. Or maybe you just want to change the look of your guitar. But not all tuners have the same footprint, or even use the same hole size. Many modern tuner sets have little locating pins to help with alignment. The location, and number, of these pins varies by manufacturer. So care must be taken to drill in the proper location, otherwise the tuners will not fit correctly.
This customer wanted to replace the very cheap tuners on his no-name Esquire copy with some modern 19:1 ration Kluson tuners. Smart move. I have a little jig for installing tuners that makes this job relatively easy. Of course, you still have to take care that the center line is correct…otherwise the row of tuners can be wonky.