Pretty much all the micro switches I've seen (both leaf and micro actually) have been 0.187" (typically red). You can buy them super cheap on ebay. I think I got 100 for well under $10 shipped, but you might be able to do better. And yes, they should not fall off. Either manually tighten them (as others suggested) or if they are really bad (rusted, corroded, damaged, etc), just replace them.