How to Remove the Switch to Repair Internal damage

"The trick is to dismantle the machine from the bottom up. Put it upside down on your workbench. Take off the cable box. Then remove the motor cover. You need a 8 mm hex wrench, a Torx and a Pozidrive #2 screwdriver. When the motor cover is off, you can push out the hinge axle. Voila! I found out the hard way. But here is a neat movie on YouTube. https://youtu.be/Hw-L6Dk9eL4

I, too, had problems with the switch. Somebody had cranked it up too far, and now the speed would start at maximum and the you had to crank the speed down not up! Another symptom is that you can turn the speed knob 360°, not just 180°. Unfortunately, the spare speed regulator is sold out.

I found the solution only at the second attempt. It depends how the spring actuating the speed knob is put in. The left limb of the spring holds the swivel actuating the maximum speed switch. No problem here! The right limb of the spring has to put in in a way that it obstructs the path of the white pin sticking up from the dial. If put in correctly, you can turn the knob 180° only. If the right limb of the spring it above the gray plastic edge, it will not engage the pins on the knob, and the knob will turn 360°. Just put in the left limb of the spring correctly.

That's it!"