German Tandberg Service
I have no experience with this service (yet) nor am I affiliated with the company. It seems to be the go-to place for repairs and fully refurbished units in Germany though:
The Tandberg Central Service is managed by Mr. Jochen Schmidt. I have been there a few times and have also purchased some refurbished Tandberg Hifi devices from him or had them repaired by him. I would say that the Tandberg Central Service is the best address in Germany when it comes to Tandberg Hifi. Mr. Schmidt is very helpful and very competent. The prices for repairs are reasonable. I can absolutely recommend the service.