I've found that if you put a small spring-washer right next to the latch, the washer keeps a constant amount of friction on the latch no matter what its orientation, and no matter how worn it is.. It's not exactly easy to do, but it totally eliminates latch flopping. You have to remove the latch with the method of your choice, file away a little bit of the handle to make room for the washer, stick the washer and latch back in there, and find something to replace the latch pin that you just destroyed. It costs nothing, and it works so well I don't know why manufacturers don't do it to begin with.
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j rainey