How do I fix a leaking mixer tap?

I have a BlancoOxi 9001 Mixer tap and it is leaking from the top where the alan key is

steve mott
December 2009

i am a plumber look at the back of the tap where it swivels there is almost certainly a retaining screw probably small allen key fitting if so take out and twist stem whist pulling upwatrs there ai a position whilst swivelling the stem to allow it to come up and out replac o ring exact opposite to refit you can do this without tuning stopcock off

bluebird4211
April 2008