Thank you very much RPM55,
I guess I can see on picture 1 the rather thick copper seal versus the thin alu seal at the filter. It was hard to see where it leaks without removal of that plastic cover and by tomorrow the fuel will be evaporated...Is there any other way except driving to see where the fuel comes from. Will idling do it?
Thanks again for your help. I'll probably replace the rubber hoses as well as the filter with the washers.