Shelley, (Temecula, CA)
Shelley, it would be difficult, at best, to try to ascertain a correct diagnosis without actually viewing or analyzing the carburetor on your generator closely. But it certainly sounds plausible, depending on the age of your unit. Unused fuel will deteriorate and become gummy over time, turning to a varnish-like material. Chances are the carburetor on the generator will need to be rebuilt at best; replaced entirely at worst. Either way, the generator will have to be tuned-up and set up with a load bank and all adjustments, (choke, carburetor, governor), set to that unit’s specifications. I'm not aware of regional repair costs or the prices of new equipment but I would certainly get a second diagnosis just to be sure. But it is quite likely your service shop is correct.