I have flipped the prop 180 but haven't been back out on water to see if that helped. Hole is round but is notched on the inside for the drive/shear? Pin. I will look into how to check balance on mower blade and see if I can do something to check that out. The mka-47 bracket could be tightened up with some minor modification, but i think it would still make a lot of felt vibration in boat. Other than this issue, I love the I plot link and can't wait to get it figured out. Thanks for the help!
Ty