Maytag MMV4184AAW noisy and not heating

Greetings list:

My Maytag MMV4184AAW over the range microwave stopped heating and got noisy when running. All controls, lights, and turntable are working fine. A brief web search stated that the magnatron, capacitor, or transformer may have gone bad.

Can anyone advise to troubleshooting and procedures to repair, or should I bite the bullet and replace the 12 year old unit?

Thanks in advance!

Scott