Mine was doing that and at speeds over 65 it wouldn't move unless I helped it along with a hand. I took it to dealer last fall before my warranty ran out and they replaced the mechanism, bushings, arms. They replaced all but the shield and outside brkts just to make sure they fixed it.
I actually R&R all the parts before, and I think It may have been fine if it was all cleaned and lubed, but with warranty running out I wasn't taking chances. You do need to take off the plastic to properly clean and lube the tracks and bushing that ride inside them. There is 4 tracks and 4 square plastic bushings that ride in the tracks, this is were the dirt and binding is occurring. So you need to take it all apart to get all the dirt out, and there is a sh*t load of dirt. The FSM says to use lithium soap base grease. I use a lithium base grease with Teflon in it only because I have it in the boat biz. It's made by Mercury and called 24C. It's made for stuff like this, it resists water wash out, and the Teflon makes it more slippery for friction parts. Just don't use it on needle brgs. You can get it in squeeze tubes. I think cleaning and lubing with any quality grease is better than not and I don't see how it could hurt it. And a little grease goes a long way, don't over do it.
Also there's a lot of little bushings, and washers holding the arms to the assembly, and the bushings are not all the same, and the washers go in a certain place so I would recommend you do one side at a time so you have the other for reference.
