OK, managed to fix the decompression lever. Opened the little front (exhaust?) valve cover, pushed the rod outwards and all seems fine now...decompression works.
gunnerbuck...thanks for the tips, you were right, no loctite, just the gasket, which was fine so I cleaned it, oiled it and reused it.
Just two more questions:
1. Do I have to bleed the oil circuit now (because I took of that cover and a rubber hose leading to/from the frame?)
2. Would it be good to check the valves when taking of the cover? (valves had been checked around 1000 km ago as a part of 15000km service interval checks, oil change....and stuff)