I drill on a sidewinder, but it's the 3600. I've never tried to change the speed, it works fine as is. Have you checked to be sure the motor hasn't been replaced with a higher RPM motor? I've also never checked the RPM on mine, but most posts I've seen here say around 500 is what most drills are. I do have a manual for a 2500 if you don't know what speed motor is supposed to be on it. -- JohnP