[Linked Image from thumbs2.imgbox.com]

Looks like it was made @ Hänel where they were completed by the most competent mechanic Gebhard Helmuthhauser / Gebhard Helmuthäuser or Gebhard Helmuthäuser who was listed @ Bergstraße 1 or Gebhard Helmuthhauser / Gebhard Helmuthäuser or Gebhard Helmuthäuser was sourced for the tube work. Evidently he had a difficult time spelling his name or I do one????

The Suhl Proof Facility was purportedly going thru a ReFurb about this time?

Hochachtungsvoll,

Raimey
rse