Guys, after going to 2 dealers last fall and finding no solution for the deck vibrations (harmonics) I finally got my 52 HD out and decided to fix it on my own. After looking over it was obvious it was related to the tensioner. If you look at the way the arm was designed the pivot point gives the idler pulley twice as much mechanical advantage over the spring. I ended up machining a new arm with pivot point that is twice distance giving the spring the mechanical advantage. The vibrations are about the same however the horrible noise is now gone! The spring vibrates half as much as it used to. If you guys are interested I can post a picture of what I did.