Drill a 5/16 hole from the back of the handle for better centering
There are a few subtle details that will make your window regulator handle rebuild go smoothly. Once the handle falls off of the metal part of the regulator handle, loosen the hex head screw and remove the handle assembly.
If you have reached your threshold for mechanical projects, you can buy a rebuilt handle. If you are still interested follow these next steps:
Using a 5/16 drill bit, enlarge the hole in the handle end of the assembly, from the back side of the handle. The kit includes a new knob, but the inner shaft of that knob is of a larger OD than the original knob. Next you can fit the knob washer and press rivet together in the 5/16 hole. If you have a small arbor press, you can press the pieces together, but be careful to apply even pressure to avoid crushing the plastic inner shaft. You can also hit the head of the rivet with a rubber mallet, but do so using care and an even swing.
With the kit installed, it is good as new!