If it's a single lever tap supplied with the sink, it will probably be an Osprey. Allen screw accessed under the little red/blue push fit button. Undo and lever pulls off. A strap band grip will help unscrew the cone shaped cover. A taptool will unscrew the cartridge cover, for cartridge replacement. Spares obtainable from Central Services 01782599258.The instructions than go on to say 'o'ring renewal is via unscrewing the next bit of the body section to then lift the spout off, but I don't believe it yet. Brute force unsuccessful.I will probably have to disconnect pipes and remove tap as the final act of 'o' ring replacement.
Bob, February 2009
