Alpha 1 vibration only when trimmed full down

[indy440]

i have a alpha 1 gen 1 on a 22' wellcraft with a 350. While on plane with the drive trimmed all the way down there is a noticeable vibration through the hull. As soon as i trim it up, even just a little, it completely goes away. Ujoints seem good. Engine alignment is not horrible but not perfect either. Gimble bearing feels fine turning it by hand. It has an aluminum 19 pitch prop and there is a small rock mark on one blade.

 

[Rick Stephens]

I've noticed the same kind of added noise when the drive is fully extended and locked down all the way. Two blocked, seated down with no wriggle room it passes more noise to the hull.