Hello Sabine,
Your machine is totally gorgeous, and I am so glad that you found the posts on my blog helpful.
German bobbin winders can be totally mystifying. They weren't necessarily made by the same manufacturer as the rest of the machine, which is why you can see the same make and model of machine with a different bobbin winder, and vice versa.
Nifty features that you will often find are a pair of little tension discs, and an automatic release mechanism which disengages the winder when the bobbin is full.
The most ingenious feature, to be found on many bobbin winders, is the curved metal plate which feeds the thread from side to side - no need for a moving part to feed the thread. This is easily seen on the machine in the following post because it is at front on the lower part of the upright bar - see pictures 4 to 9.
http://lizzielenard-vintagesewing.bl...ders-no-1.html
This machine winds the neatest, tightest, most even long bobbin of any of my machines. It knocks spots off any Singer.
There are other bobbin winders that have this curved plate at the very base of the upright bar, towards the back, tucked out of sight (see the machines on my blog in the posts German Bobbin Winders No. 2 and No. 3). So Sabine, if you stick you finger in at the back of the bobbin winder you will feel the curved metal edge I am talking about. This is why you have to take your thread down the back of the upright bar, because the curved edge is the last surface the thread passes over before reaching the bobbin.