Rotor retention clip for Thompson L drum

[Pauliedweasel]

I have a friend who recently bought a West Hurley Thompson with a fifty round drum. When he got home with the gun he noticed that the clip that holds the drum rotor in place was missing, does anyone know where he can order a replacement? He contacted Kahr Arms to see if he could purchase one through them but they informed him that they do not produce their magazines and the manufacturer doesn’t supply the, with spare parts (Typical Kahr Arms support) and just blew him off. Anyone out there that has info on where he could get one would be greatly appreciated. Thank you.