Our piece of s--t microwave/convection oven has been replaced twice under warranty. The first replacement was at our 5th wheel manufacturer's service center and we only had to tell them what the problem was and they took care of everything including the labor to install a new unit. The next time we contacted the microwave manufacturer and worked everything out with them in advance. A local mobile tech and authorized microwave rep brought the new one and installed it no charge to us. I would always start with the manufacturer of the broken part first. Hopefully you will not have to pay a diagnostic fee again under warranty. By the way, # 3 microwave is again on the fritz and we are replacing it on our dime with a residential model that hopefully performs better and lasts longer.
