After some researching I found this picture (see attach). Most likely the problem in the footwell flap position motor (marked as M2/15 on the picture). I'm wondering, can I access it without the removal of the whole dashboard?
Btw, the original document where I took this draving
(link) is quite interesting. I.e., it shows how to replace the dust filter on W203. Yesterday I spent a lot of time on internet to find this information, removed the passenger side under dash panel and almost pulled the glove box - just to find out that the dust filter is under hood right above battery!