The noise usually comes from the motor. It's either worn out or there are some dirt in the motor. USM, SWM, SSM, HSM,...etc all of them works in the same principle. Different makers just call it different names. There are 2 major parts, stator and rotor. The dirt usually gets trapped in between these 2 parts
I'm not really sure if the dirt is carbon build up (unless your lens is burning fossil fuel
). I guess the repairman is just trying to explain everything in layman's term.
I have cleaned some motors before but mostly on cheap lenses. Cleaning the motor usually works but it has to be handled meticoluosly. Sweat from your hands could cause more problems.