2006 900 RMK…most, if not all, recommended updates. Problem started two seasons ago with a “rattle” coming from the clutch side. Very “tinny” didn’t sound like it was coming for the interior of the motor, to me anyway. I have ridden this sled for two seasons with this noise and doesn’t seem to affect performance at all. Still pulls hard!! Noise not there under power. Can ride all day without really noticing, but get back on the trail coming home and it is very noticeable. Cannot hear at an idle, but when the primary starts to engage…there it is. Have had both the primary and the secondary to the shop and the clutches are in good shape. Finally took the whole sled to the shop. Noise is there when the primary starts to engage…not when idling. Took the primary off at the shop and rattle is gone. Put a new primary on and the rattle is back. The guy at the shop has no idea…has never heard of this before. Says his best guess is in the motor because it is noticeable with both my primary and a new one. Going to start tearing into the motor this week…If anybody has an idea of what this could be, please respond. Shop costs of trial and error are adding up quickly. Thanks!!!