I thought the motors where different between the 35 and 40. One being plastic and the other metal. I also think they are designed by PUR. So I think they are proprietary.
__________________ "Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"