Hi John
that's a good question. We don't specify it by sharp vs unsharp side. The notion is pretty straightforward: you want the flattest side facing the worm gear. This is so it stays seated and if you really loosen your RA it doesn't pop out accidentally (even if it does, you can always put it back in, but hopefully with the correct side down).
if you aren't sure you can always just place it on a surface and do that test, and whichever side is flat (or flatter) is the side facing the worm gear.
hth
Brian?
