When an instrument is brought to the shop, I first check to ensure that all the seams are glued. (I give a little pull all around and look for movement because sometimes seams are not glued, they’re just sprung shut.) I check for cracks everywhere, especially from the A–string peghole. I give a light tug upwards on the bottom of the board to make sure it’s glued down at the bottom of the neck (look for a gap when you lift the board).
I push the strings aside and make sure any grooves in the fingerboard are minimal. I measure string height at the end of the fingerboard (the maximum E–string height should be about 3.5mm to the center of the string and the maximum G–string height should be about 5.5mm). I almost always end up pulling the bridge back because most players don’t pull it back far enough (the back side should appear to be perpendicular to the top), and center the strings on the board, make sure the center of the bridge is aligned with at least one of the f-nicks (sometimes the nicks aren’t level) and perpendicular to the center of the instrument, or in the place where the bridge has always been, if that’s evident and it doesn’t sound worse there. Moving the bridge in any direction definitely affects tone, so I’ll do a quick check to make sure I haven’t adversely affected tone.
Next I unscrew the fine–tuner screw, rub a candle on the threads, and push a little wax into the hole. I check string grooves at the bridge to see that they’re not buried in the bridge; at the nut I make sure they’re not so deep that the string is hitting the board at the nut but is always slightly above it. If any strings are looking in the least shabby, I suggest the owner replace them.
Finally, I ask the owner if there’s anything else wants addressed in terms of playability, tone or appearance. Finally, I wipe all the rosin off the top (for home use, I particularly recommend Stewart–MacDonald’s Preservation Polish, used very sparingly), and hand the violin back.
Generally I don’t look for “theoretical” problems caused by a different approach to instrument construction than my own unless the result is a serious tonal problem and it can be fixed. If someone likes his or her violin, it’s not for me to try to talk them into something different. Ultimately, each player’s tastes and preferences are what matter most.
–Michael Darnton, Violin Maker