Kenmore Elite Microwave Problem

My Kenmore Elite Speedcook Oven started making vibrating or rattling noises in the area of the magnetron when it was turned on. The Sears repairman quoted replacing the motor/fan assembly (part # 8184876).
I wasn’t sure I wanted to pay the quoted repair price of $325.00 so I took the Microwave down myself with some help and disassembled the fan/motor from the unit. I could not tell if that $100 part was causing the noise but the resistance seemed to be okay. I then ran the micrwave without the vent fan and the noise was still there. The only other moving parts I think are the turntable motor and a little plastic cooling fan in the control area which I don’t believe are making the noise. I wonder if the magnetron could be making this noise?

Any suggestions?

You might try this link.Microwave Oven Repair Case Histories for the Brands Kenmore through Montgomery Wards There is usually a stirring fan above the cooking area, that could make noise.

if the noise sounds like it is coming from the mag when you are running it with out the fan my need and new HV diode and or cap, all so take your mag out and look at it to see if it is cracked