I'm been doing some re-fretting lately. I have been replacing frets on old/odd guitars that have fret kerfs too wide for standard fret wire and etc. I've been using the fret sizer tool, and have been contemplating the concept of fret barbs, and their holding friction. Concurrently, I have the old Tele "switch tip falling off" problem on one of my geetars. I was thinking, a barb on the switch handle bat would really cure that. So, I grabbed a set of diagonal pliers and squeezed a deformation into each side of the the switch handle. I put the switch tip/knob back on and it was quite tight. I put one more of set of deformations up further in the handle, and it was really tight. Here is what I did. The resultant barbs on the switch handle are pictured here. If you have a loose one, try it and tell me what you think. I've had trouble with glue fixes. This is a really fast solution as well. You can do it with the switch assembled in the guitar. If it is a problem in the future, you can always file them down.