HI:
I took an old speedo gear did some Solidworks modeling(SLDPRT File) used a 910 ALLOY on 3D and got what you see in the pic.
I'll have to see if Mark 1 meshes properly with its match up before I figure how I will swap the shaft to the new gear.
The 910 has a 8,100 tensile compared to 12K for Nylon 101 so I might put a piece of Nylon on a CNC and machine it from the SW file.
Got other fires in my life so it will have to sit on the back burner for a while.
Bernie