Thanks Bruce for your prompt answer.
It has run for years without the decompressor (I have no idea what its function was!) and that should not be the problem now.
Both springs are in place in the carby and the diaphragm is ok, in fact when I suck at the hosepipe end the "valve shaped thing" inside the carby opens and closes.
Please tell me how to get information from the parts list and manuals area.
If I may ask again: where does hosepipe no.3 go?
Best regards, Henry.