When you take your varaitor out look to see if the slide-guides for the back plate have worn down. Once it's out, hold the back plate and twist it in the varaitor. Check to see if the back plate is making contact with the varaitor. You may even see some metal has been removed from the inside of the variator. I have had this happen with Malossi Multivars on a Super 9 and a People, both kitted. If that back plate makes contact while it's traveling in and out, it will do exactly what you described