Hello Friends! first time posting here. So I've had this Sears Electronic router since I can't remember when. The model # is 315.174770 . I'm unable to find the exact manual for this router but I did manage to find a router manual on the Craftsman site for a router exactly similar to my model physically. Only thing is, this manual is applicable to one labeled as 1 1/2HP. In any event I'd kindly like to ask anyone who might know when/approximately what year this particular model may have been available also anyone know what the intended purpose was that the separate ring with fractional graduations rotates independently of the main adjusting ring?