Expert: Martin Meyer - 9/19/2007

Question
Hello,
I have a Junghans wall mounted mechanical clock which counts the hour and gives sound every half an hour.
The hour is ok, however the "half hour gong" goes off at 25 past. It should go off at half past.
Also at full hour, for example at 9 o'clock, I can hear 9 "bims" and only 8 "bams" and at 25 past the missing "bam" goes off.
Is there anything I could do with that?

Answer
Hi Radek,
    First, make sure that both keys are fully wound. If the problem still occurs, I'm afraid this is a job for a professional clock repairer.
    The bim-bam sound is activated by a rotating star-shaped wheel in the gear train of the movement. One of the hammer tails may be bent, causing the last "bam" not to complete. But the problem may also be caused by an incorrect indexing of the star wheel with the other gears in the gear train. In this case, the entire movement must be partially disassembled, and the indexing corrected, which is a very difficult operation. You could try bending the hammer tail back to its correct position, but the chances of correcting  the problem are not great, and there is a real possibility of breaking off the hammer tail. I would leave this problem for a clock repairer.