Reinhard Zieglmaier has contributed to the search, informing having met with the boat in the nineties. Stating she was built 1993 at Bültjer.
Here is the registration link to the boat, which he believes is the one your are looking for:
We are trying to find the name of the former owner and will inform. As owner data is confidential, please tell me your e-mail address and we will send info outside of this forum.
Here is the link to the boatyard. You may want to contact themas well: