My blower keeps having valve problems. First time: ZERO compression; the rocker arm for the valve popped off its position, and it was holding the valve open. 2nd time (now!): monster compression, we can't start it because it can't hardly be turned over. I believe the valve adjusting nuts are creeping loose, and the valve timing is all wrong. Right now it feels like about .040-.050 clearance, and we would like to re-adjust. Unfortunately, I don't know how. The gap is tiny, and nothing we have can measure the gap. Also, I have no idea what the proper valve lash is. View attachment 177293 Any advice? Does anybody know what Stihl has to say about keeping the valves from changing, and is there a history of this problem from other owners?