The problem continues.
Since last post the mount holes had a tap run in them, cleaned with acetone, and the bolts replaced with allen heads of proper length ( 90% of available hole thread) and both hole and bolt had locktite.
The #2 Ryobi has been on that mount for about 3 quarts of fuel. This morning while running a tank I heard a slight 'pop' over engine. Shut down for inspection and found not only lower port side mount bolt head sheared off but 3 cracked areas on the mount itself.
The site of sheared bolt shows no fatigue cracks.
The mount is 3/16"+ thickness on front plate.
This has me more than just scratching my head! Could sure use some input as to causes and solution(s).
Pics if they will help