See photo of how I fixed that damned thumb trigger ... I ground a groove in it and inserted a nickel so it was locked into position to run every time I squeezed the finger trigger. Prior to this, every time I changed hands, I had to pull back the trigger with my thumb while also squeezing the finger trigger ... this is a hell on my arthritic fingers/hands! This needs to be redesigned so the thumb control can be locked into position.