The problem arises because the spinner backplates are a hard alum. whilethe YS drive washer is amuchsofter material. The addition of the roll pins is a very good solution. Analternative method, which may be easier to implementis to use 2 small 4x40 allen headbolts to secure the spinner backplate.I have used the bolt method forover20 years. The props stay tight with only normal tighting of the prop nuts.

John W.
Scottsdale, AZ