Hi @Poppo,
Reading about your old harp, I realized that I also have one of these! I bought it new some time in the late 1980s or beginning of the 1990s.
I almost never use it because I prefer the more expressive sound that can be obtained using draws on standard blues harps. Also (see below) compared to a standard blues harp, it seems to require frequent disassembly and cleaning – and that is a lot more work than it is on a standard blues harp!! 
This model is no longer produced. The valves used in it are (as they are in true chromatic harps) always a problem: sticking, making unwanted extra noise, etc.
Greetings,
– Slim 