Your connecting rod is a tad thicker making it slightly hit the inner bottom of the cylinder skirt on the cylinder when the rod swings around. If you pull the cylinder back off and closely inspect you'll see slight markings on the connecting rod and the inner bottom of the skirt. Take a Dremel or a file and clearance that spot and you'll be good to go. I've had this happen on a few AV7's but never a AV10 yet.