I got one on eBay from China for 49$ and it works and fits perfectly. Amazon sells one as well for just a few bucks more

I used to have a 510 (loved it) then moved to oly mirrorless. The Olympus 50mm macro for 4/3 is an outstanding lens (imho). Used copies on ebay are pretty cheap. It would be worth it if you can afford it. I know that doesn't answer your question but just a suggestion.