Hi mate, Firstly What type of system to do you have, Sealed, Gravity or a Combi. Are you sure its an Airlock as thats Extremely RARE especially being in just the Basin Tap.
Few things you can try.
- Try removing the filter (gauze) in the spout of the tap, it generally screws off and give it a good clean.
- Do you have Stops valves fitted??.. if so, take them off and try without them.
-Could be a dodgy tap, replace and try a new one.
harry, February 2008