I was called to a property in Chadwell St Mary near Tilbury . The inside handle was rotating and not working the mechanism . I removed the handles to find the section where the spindle goes through had broken up. The mechanism was made by GU and the older style Gu centre case in no longer available apart from some very bad copies . I ordered the new style GU mechanism which went straight on and only had to move the centre keep i also fitted a new cylinder so every componant is new.