I've seen a few broken and bent cams over the years in various engines. My cousin bought a new mower from one of the Big Box stores last year. She hadn't mowed with it an hour until it started making the worst clanging and banging noise you ever heard. She called me and asked me to come by and look at it. Large, single- cylinder Briggs but can't recall the HP now. I wouldn't touch it due to voiding her warranty since I wasn't certified. I told her it was either the governor gone out and flopping and banging around, or the cam jumping up and down, possibly with teeth knocked out. Countershaft or balance gears gone perhaps. No way of knowing w/o disassembly. We hauled it to the shop who did the warranty work and the owner was a former student at the same small engine mechanic class I attended! He's got his own shop out on the North end of town with several mechanics working for him and from what I saw was completely covered up with work and a 3 week waiting list. Me? I've got my driveway and several shade trees and no overhead! Oh..it turned out to be a broken camshaft. Broken clean in two but still holding enough to run amazingly! You couldn't pay me to run a shop these days.