My most used power tool is a 5" Milwaukee angle grinder. It gets used for grinding, cutting, and sanding. This particular Milwaukee model has a variable speed dial, but I never use it. I always run it at full speed.
For the last few month the variable speed feature has been acting up. Even though the dial is set for full speed the tool will only run at a slower speed. If I turn it off and on a bunch of times it eventually works, but it has been getting annoying.
I decided to take it apart and see if I could bypass the variable speed unit. In the above photo you can see the speed dial and the black electronic control unit just to the right of the screwdriver.
I made up a short jumper wire to bypass the electronic control. I used crimp connectors that I also soldered. I have found that this is the most economical way to make long term reliable electrical connections.
Better connections can be made with high quality closed end crimps and the proper matching crimp tool, but these are surprisingly expensive and not readily available. If you are working on marine wiring it is worth it. For most jobs generic crimps that have been soldered work fine.
This photo shows the jumper wire installed between the switch and the brush holder. I left the original wire in and simply taped up the end of it. The hardest part of most power tool repairs is fitting everything back in the case. It took several tries to get all the parts and wires in the right location. It no longer has variable speed, but now it starts reliably every time I hit the trigger.