( First, I had some shopping to do ) Since the new head will require a new mirror bracket, and another method to hold objects to be cut at the correct height, I haven't yet given the new air assist system a tryout. I'll need to realign the optics once the new mirror mount is fabricated and installed, then I can give the new air assist system a test drive.
I considered buying the motors from Sherline, but they want $65 apiece for their stepper motors. I knew I wanted NEMA 23 size motors, with reasonable torque, voltage, and current ratings, and dual shafts (the mill handwheels attach to the other shaft). So I checked the usual suppliers, and ended up buying a set of three from a seller on eBay.