if your door lock dosn't work correctly when its in open possition then your your lockstrip has failed,the only way to rectify this is to replace the lockstrip,you will need to write down all the numbers and the make off lockstrip and order 1 thats same,if you havn't got a supplier in your area you can order online at many places like northwest hardware,to replace you will need to take handles off then remove cylinder by taking screw out of lockstrip that is level with cylinder then take all remaining screws out of lockstrip before it will come out then replace with new.hope this helps
shaun www.sdwupvcrepair.co.uk
March 2008