First you need a Tap Reseater Tool from your local hardware store. Then follow these instruction:
1. Remove the whole head of the tap including the washer leaving the base and spout.
2. Screw the reseating tool into the body of the tap and alter the tool until it is in contact with the seat.
3. The tap can then be reseated by turning the tool to grind down the seat.
4. To check if the grinding is complete, look at the grinding disc, if black marks are observed then the seat requires more grinding, when they disappear completely the tap is sufficiently ground.
5. Reassemble the tap in reverse order to complete the job.
These instruction by large I got off another website. They were so simple I had to share...
Ben 10 Plumber, July 2009
