If you're interested in the Trabant, the Youtube channel Aging Wheels has a couple of playlists where Robert has rebuilt the engine and gearbox of his [1] and just general videos [2] about his Trabant.
[1] - https://www.youtube.com/playlist?list=PLzV2uljPvyAeEgAEgwYNf...
[2] - https://www.youtube.com/playlist?list=PLzV2uljPvyAe1K8ArgPHG...