Early in January, the few shops in the Communist half of this divided city where residents can buy tape recorder cassettes were all sold out.
One reason suggested by some East Germans is that on Jan. 2 and 9, an allied radio station across the dividing wall in West Berlin broadcast, as it had previously announced it would, the lenghty text of a sharply critical "manifesto" that allegedly was produced by an opposition movement within the East German Communist Party and slipped to the West German magazine Der Spiegel for publication.
In this way, the manifesto can now be secretly distributed via the cassettes and pondered privately by East Germans, much as copies of a manuscript of a recent and similarly critical book by an East German economist, who is now under arrest, are said to be circulating here.
There may be other explanations for the disappearance of cassettes from the shelves: Christmas buying or perhaps recording of a rock concert broadcast by the same jointly operated U.S. West German "Radio in the American Sector."
But it seems clear, sources here say, that while the official flap between Bonn and East Berlin over the document's initial publication has cooled down, the alleged manifesto continues to produce tension and uneasiness beneath the outwardly calm East German surface.
For example, East German Premier Willi Stoph, generally ranked as No. 2 behind Communist Party chief Erich Honecker, has not been seen publicly here since about Jan. 16. He did not show up yesterday to greet the visiting Angolan prime minister.
Ordinarily an absence from public view for a few weeks might not be important. But the situation has taken on considerable interest in many quarters here because Stoph is one of the few top-ranking party members who was not singled out for sharp personal criticism in the published manifesto.
The premier is also considered as a political rival of Honecker, perhaps the likely one to succeed him if a change is brewing, and perhaps even more in the Soviet camp than the current party leader.
The idea that there might be a group of dissidents within the East German Communist Party or that Honecker may be losing his grip also may be making Moscow nervous about the political stability of a country that, officially at least, is its most devoted ally.
The East German Party newspaper Neues Deutschland -- perhaps as a reminder -- has published several items in recent weeks relating to the Soviet army units stationed in East Germany --
The Soviet ambassador to East Berlin, according to published reports, has talked publicly recently of the "unbreakable union between our countries and peoples that naturally bothers some people in the West and they pour strams of lies and invective over us."
Aside from a sharp attack on the East German form of communism, the alleged manifesto contained charges of personal corruption and nepotism against Honecker and other officials and a strong attack against the Soviet Union as well.
The editors of Der Spiegel claim that the manifesto was written by a group of medium and high level officials within the ruling Socialist Unity Party in East Berlin, but they refuse to disclose the names for fear the authors will be jailed.
The East Germans claim that the paper is a fraud, concocted by West German intelligence agency.
It is clear that neither Bonn nor East Berlin wants any severe strain in their relations. Bonn wants to keep the doors open so millions of West Germans can continue to visit in the East, and East Berlin wants to continue trading with and getting credit from the West to help an economy that is stagnant and at the root of potentially far more serious problems.
Some West German political figures have cast doubt on the authenticity of the paper, questioning whether it was authored entirely by East Germans.
Foreign intelligence sources and diplomats generally seem to feel that the document was probably written by East Germans but that it was probably a small group and not at high levels within the party.
"The security apparatus here is simply too pervasive for that to happen," explains one East Berlin resident. "I tend not to believe there is really any organized opposition because it's impossible for more than 10 people to get together without one of them being part of the security service."
Still, foreign observers acknowledge that while there is nothing overt happening here -- with the exception of Stoph's absence -- there are no outsiders who know what is going on inside the ruling Politburo. Some East Germans reportedly have expressed fears that a security crackdown is coming, and there were some signs of nervousness at the outset.
East Berlin closed the Der Spiegel office here, denied entry to the city by a leading West German opposition politician, and the Soviets stepped up their patrols in West Berlin in the immediate aftermath of the publication.
Ironically, the alleged manifesto probably caused more public commotion in West Germany, where Der Spiegel devoted several issues to it and the newspapers pondered its meaning daily.