microwave cabinet fan runs when door is opened, magnetron does not power and fan does not come on

I found the primary interlock switch faulty on arrival, replaced and still had the same issue. The fan that comes on when the magnetron is active is only turning on when you open the door. I confirmed all the micro switches were functional at this point. My experience in the past is that one of the switches would cause this. I am suspectin that I am missing something here.