If the basin mixer drips from the spout, the issue can usually be resolved by replacing the cartridge.
This video applies for..
10000 Steel Wave 10006 Steel Wave Sand, 10007 Steel Wave Amber, 10008 Steel Wave Shadow, 10015 Steel Wave High, 10016 Steel Wave High Sand, 10017 Steel Wave High Amber, 10018 Steel Wave High Shadow, 10020 Steel Clear and 10028 Steel Clear Shadow.
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