So, there are 2 versions of the jack shaft(JS). They have 2 different tensioners. The old style used a spring that connected to the upper right JS cover holder. The roller on this one was small and this was not a good system. That is the one I had. The new ones (that have been around awhile) have a spring that wraps around the tensioner post and connects to a "tab" for spring pressure. Anyhow, I was about to pull the plug on another Promod JS, but I called Monster Scooter for an availability check and they gave me a 5% internet code of AR0095 so I could not resist. I know I am going to kick myself long term for not getting the Promod JS, but I am pretty sure we will move on from mini bikes to street legal Honda Mini Trail clones over the next few years.