Intermittent door switch(s)

This is a combination microwave-convection oven. At times it works perfectly and at others it will not turn on. I believe the problem is in either or both of the door switches. If I look up the parts, listed are two switch interlocks Part [COLOR=#0066cc]AP2024367[/COLOR] @$18.29 each, a switch monitor [COLOR=#0066cc]AP2024325[/COLOR] $17.69 and a switch lever Part [COLOR=#0066cc]AP2016540[/COLOR] $2.89. How can I tell which one(s) I need to replace. My guess is the switch monitor but is that the most likely since the problem is intermittent.

The monitor switch is a safety device which has nothing to do with this problem. Most likely the problem is a bad interlock switch (top one). The best thing before ordering any part is to remove the outer case and check all switches. Guessing can make repair more expensive.

Gene.