Took it to the dealer. Heard back the next day it was an "anti-backfire solenoid" (connects to carb)which he could order and replace or just disconnect. I went with the no charge route - disconnect. $29.50 for labor. He was out when I picked it up, so I didn't get to argue that this should be a warranty issue on a 3 month old mower. Am I right? And anyone heard of an "anti-backfire solenoid" ?