Anyone else have one of the JS600 models. I've had the thing a little over a year and it started acting up on me. With the speed control set all the way to the slowest setting the saw would speed up then slow down speed up and slow down. I wasn't cutting any material with it when it was doing this. I made myself a little box that you can put the jigsaw in and use it hands free kinda like a band saw. Anyone else had any problems out of there jigsaw.