That part tends to fail quite often , I know its a long shot but if you have a 3D printer or know someone who does you can print it out a strong material like PTEG ,Carbon or PC. I had to design that [link|https://www.thingiverse.com/thing:3659439|part] when my August lock broke. I couldn’t find the part anywhere. Contacting August did not help either. @Jayeff , he’s suggestion is great , buying a broken AS IS or used lock will probably be the only way to get parts.