As Alan has already mentioned there is a screw on the bottom of each handle for tension adjustment. However if when loosening these screws it may still feel a bit sticky. I had this happen a couple of years ago. My remedy was to remove the screws, the spring and finally the plastic button (this button rubs on the bottom of the handle, hence the friction adjustment) and apply a bit of plastic compatible grease on it. I now have nice smooth move handles on my Z4000.