Unless the handle is perfectly horizontal the lock will not auto double lock because the cut-out in the handle control washer does not align with the auto deadlock actuating pin.
With the lock disassembled the handle is free to rotate and makes no attempt to auto centre. The handle seems not to be spring loaded and its position is solely dependant on the bolt slide which due to the design allows it to flop down a bit and stop the auto deadlock from working.
What part of the mechanism should keep the handle horizontal and what is likely to have gone wrong with the lock?
Thanks