A chapter of the nonfiction book "The Unexplained: Great Hauntings" (1984) is about the Rosenheim case. The chapter's authors Colin Godman and Lindsay St. Claire in 1975 traveled with a camera team to make a BBC television documentary about the case. I presume this footage was featured in "Arthur C. Clarke's World of Strange Powers." Here is an excerpt from the chapter.
On 20 October 1967, the office lights suddenly went out with a bang. Herr Bauer, an electrician from Stern's, a local firm, was called in to repair them. He examined the lights and found that each fluorescent tube had been turned 90 degrees in its socket and disconnected. He had finished replacing the tubes and put away his ladder when there was another bang. The tubes had twisted and disconnected themselves again. He was even more puzzled when the office staff told him that the automatic fuses in the office ejected themselves for no apparent reason, sometimes on all four circuits at once. Bauer began a full investigation of the office wiring and equipment, all of which he found in excellent order. He confessed to Adam: "I was faced with a puzzle and called it 'witchcraft.'"
The Elektrizitätswerk (German electricity board) was asked to take over the investigation. Auxiliary Works Manager Paul Brunner found inexplicable voltage deflections occurred in the office and was quoted: "It became necessary to postulate the existence of a power hitherto unknown to technology, of which neither the nature nor strength nor direction could be defined. It is an energy quite beyond our comprehension."
Physicists Dr.Karger and Dr. Zicha monitored experiments in the office and reached a comparable hypothesis.
While measuring sound levels, they noticed that, although no sound was heard, their monitor showed a huge deflection, so they concluded that there must have been direct pressure on the crystal in the microphone. They speculated that a similar invisible force could be acting on the pen of the Unireg [electrical instrument showing voltage fluctuations] itself, causing the unnatural loops directly, independently of the electrical current. They speculated further: the same force could be acting on the tiny springs inside the telephone, bypassing the dial. It was active only for short periods, its nature was complex and it was not electrodynamic. Known physics could not explain it.
The entrance to Herr Adam's office was at Königstrasse 13 in Rosenheim.
Seven previous blog posts are about my research of 'talking poltergeist' cases during the 1990s.
Karger and Zicha also felt that the telephone anomalies suggested that an intelligent force was at work, because it had 'chosen' to focus its attention on the speaking clock.