Discovered that mine were seized solid and the tracks have flattened the roller on one side. Kinda hard to see if they're turning when you're driving it!!! LOL Anyways problem is I have the early style top roller with two bushings. I would like to replace with newer style roller, like came with the AG-6. After spending 3 hours taking them apart I now realize why they changed the design!!! Please email me if anyone has an extra set or parts for one. I am also going to call Zimmerman's