Looking at picture of pulley. You reinstall the three set screws into the plate that has 6 holes (three of which are threaded for the screws) but do not tighten. Place pulley back onto shaft with belt to make sure it is on the right distance. Now start to tighten the three screws (in a tightening pattern you would use when putting on a car tire). These screws press against the collet and tightens it. Side note, the small hole on plate, has a very small set screw which is used to lock the plate , which is threaded onto the collet body. Since this has not been altered, at this point ,you do not have to touch.