I have a 18hp vanguard engine. The problem I'm having is that only one magnetron is firing. I assume that the one not firing is bad. I am wondering if anyone has the correct part number for this magnetron. I have found part #492341, but when I look it up it does not include the 18hp engine. It only go up to 16 hp. I just want to make sure I have the correct part number before I order one. Can anyone be of help?