I live in an old house, built in the mid 1860's and much to my disgust I have been finding that after 150 years or so, some of the door locks have been failing. The main cause is broken springs on the latch. I do a lot of metalwork and into re-cycling/reuse so tend to reclaim odd bits of metal for making garden ornaments. I happened to strip down an old wiper blade and realised that the blades I have contains about 40cm of flat spring steel, 1 X 7mm which is absolutely ideal for making springs to repair my locks and other things!!