Bent Exhaust Valve Pushrod

I have a cyclone rake leaf vacuum with a 9 hp B&S Vanguard engine that suddenly stopped running and then would not turn over using the pull cord. I noticed it had been backfiring through the muffler when starting or when the throttle was reduced so I suspected the values needed adjustment. But when I pulled off the cover plate I noticed that the exhaust valve pushrod was separated from the rocker arm and upon further inspection I found that the pushrod was slightly bent. Also, using a magnet wand tool found a small amount of very fine metal shavings down near the bottom of the pushrod coupling on the cam. Before I install the new pushrod, has anyone had a similar experience? I am wondering if this was just a loose valve problem or I need to look at the cam or compression release.