I've been a music teacher for 30 years and I absolutely hate fixing string instruments! Tuning pegs don't stay put. Fallen bridges. Loose strings. Broken strings (I don't mind steel string guitar strings or truss rods for some reason). Bows. Stuff rattling inside the instruments. I hate it all. The instruments are very easy for kids to screw up.

I don't mess with sound posts or actual repairs.

My most satisfying type of repair is scavenging parts from two busted instruments or cases to make one good one.