Answer Hello Roy. You will need to check the magnetron WB27X10735 and test the diode WB27X1160. Remove the magnetron and look for burnt spots and cracks in the magnet. Also test the diode and see if it is good. It should only read in one direction. If it reads both ways, the diode is bad. You can test this with a multi-meter TJMA-DMT3. Here is a link on how to use a multi-meter. Hope this helps. http://forum.appliancepartspros.com/oven-repair-including-ranges-cooktops/4810-how-check-continuity-ohmmeter.html Read More... Answered by AppliancePartsPros.com | Friday, August 5, 2011