Here's a new old stock Master Rotor that replaces the original roller rotor with a wiper rotor. The main body is die cast and very thin. I would think you would have to start out using a new timer shell when installing one of these rotors and not a chewed up old one that the wiper could get stuck on and break.
Here is the patent for Morse’s complete timer using his
“Master Perfect Contact Rotor”, but I was unable to find
the patent for the rotor only. He mentions a application
serial number of 522,977 filed December 17, 1921, but
I could find no further documentation.
E. L. (Errett Lucas) Morse
Assignor to White Brass Castings Co.
Chicago, Illinois
Timer for Ignition Systems
Patent number: 1474376
Filing date: Jul 17, 1922
Issue date: Nov 20, 1923
http://tinyurl.com/2f3d7tx
http://preview.tinyurl.com/2f3d7tx
Regards
Art