The catch had broken on the extending handle of a pruning lopper (see photos below). On dismantling I found that a locating lug had broken (it was made of a cast metal). It was the second one to go on this tool, and I repeated the last repair which used a cut and filed down 4 inch nail to replace the broken part. Otherwise this is a good pruner, so spending about 30 minutes on it was well worthwhile. Luckily the catch is held together with removable pins, other designs may not be so easy to work on. A vice and good files are pretty essential for this repair. There is a video slide show here.