Frank,
there is a Walter Geist in Bad Driburg:

Am alten Postweg 24
33014 Bad Driburg
Germany

Tel. 0049-5253-3578

I'd phone between 6 and 8 pm during the week or on a Saturday afternoon or Sunday morning 10-12. I'd rather write a letter.

Do you speak German? If not feel free to ask me for assistance. I could make that telephone call for you if you like.

Gaby