> The terminus was then called Klusberge and I don't think there was a loop then.

If I remember correctly, there was a loop at Klusberge at the time, but it was not in service because of track deterioration. So the stub-end was cut in. This was at the time when the tram system was about to close for the first time (out of three such attempts!) at the end of the 1980s/beginning of the 1990s at the end of the DDR's existence due to tram infrastructure deterioration. So this photo is an excellent illustration to what was going on with Halberstadt tramway at the time.

Again, all of the above is written under 'if I remember correctly' disclaimer - I didn't find any confirmation on the status of the loop at this time upon a quick search.

However, a map from 11.1971 clearly shows the loop at Klusberge. In fact, this was the only loop on the system at the time, as all other terminals were 3-point (and the current terminal of the Line 1 near the depot still is). In addition the following 05.08.1987 photo shows the loop at Klusberge still in operation:
http://www.strassenbahn-halberstadt.de/bilder/reko/28iv.htm

The loop was in operation. It was used by the one-way wagons with trailer wagons. The two-way cars that traveled individually mostly drove to the stump end.