you need a new barrel.
on the lockstrip (on the edge of the door) there is a retaining screw directly in line with the barrel, remove this. turn the key a quarter turn and pull out the barrel.
measure whole length of the barrel, then measure from screw hole to both edges. for eg. 50mm/40mm 45mm/45mm 45mm/55mm and so on. b&q or screwfix sell euro cylinders although you will get the exact size online. building plastic firms also have them. you can use a different size barrel but don`t use a smaller one as you may not be able to get the key fully in, a larger one will stick out further from the handle plate.
levilewy
August 2010