I am having a problem simular to yours. The router .... has intermitnent power on off on off. I took the top off and there is a speed sensor that rides the top of the shaft and a small circuit board that has a transistor wired in next to that. I unpluged the small circuit board and it seemed to improve, which leads me to believe that the small circuit board is bad. I found this blog while looking for that board. Do you have the parts break down for this router Ryobi re 600?