We repair small, shallow dents and dings in our urethane finish with cyanoacrylate (super glue). It works incredibly well, but the area must be prepared first by fine sanding on the damaged spot with 600 grit paper, then applying the thinnest glue so it will penetrate and bond properly. There can be no shiny areas even down in the depression of the dent or it will not bond enough. If there is any de-bonding of the finish in the dent area a bit of careful probing with an E-xacto knife when applying the super glue will allow the glue to wick into the loose area as well. Don’t apply too much glue – just a little more than necessary to fill the dent. Apply more afterward if needed to fill completely.
After the glue sits a couple minutes, a very light spray of accelerant over the glue kicks it off to cure. I imagine your guitar tech knows how to use super glue and accelerant.
If I’m repairing a crack, the glue will migrate up into the crack in an amazing way to repair but I then use a bit thicker super glue on the top to prevent starvation of glue in the joint.
Once cured, the leveling process is very important before buffing because the super glue is really hard. If sanded improperly, there will be a high spot where the glue was applied and a low area all around it after buffing. To get it done properly use a utility blade with masking tape on both ends, so that the area in the middle is left un-taped, as a scraper to level the touch-up area. Then use tiny hard sanding blocks with ascending 1000, 1200, and 2000 grit papers and finally buffing the area.