Hardly any repairman positively indicates he works on the 4×4 cm TLR, the ‘Baby-Rolleiflex’. Some indicate they don’t. In most cases we can only hope that ‘all twin lens reflex models’ include the ‘Babies’. There is no point in a separate list for this camera. It is combined with its big brother. There is no other option than contacting the repair shops. I fear that parts are the main issue.
The situation with respect to camera’s of the System 6000 is bleak. Not many worked on (the electronics of) SLX and 6000 models. Now it is even worse. In this case also parts seem to be a problem. Sometimes replacing the camera looks like a better option than repair. Possibly cheaper and you will have parts for future repairs as a bonus.