Switch replacement? Kenmore 80322 1.6 cu. ft. Over the Range Microwave

A year ago, three switches, as I recall, were replaced under extended warranty. Now those switches are wearing out again as evidence by poor and uneven heat. If it follows the same failure progression, this will eventually cause the circuit breaker to trip and the microwave will be "dead". As I understand it, the door switches must work properly to ensure microwaves do not escape the enclosure during use. I'd like to find the service manual so I can replace them myself as it appeared to be an easy fix at the time. Does anybody have a link to the service manual for this model? Thank you.