I recently purchased a porter cable 892 Router and am having an issue with the clamp which holds the motor to the base. It has what looks like an adjustment screw which can be adjusted with the clamp in the open position but the manual does not discuss adjusting it. I am presently having an issue with the bit moving down when cutting dovetail joints on my jig. Either the bit is drifting out of the collet or the motor assembly is drifting down when the joint is being cut. VERY FRUSTRATING.