I took apart the vacuum petcock to clean it, and maybe do a rebuild. The usual "flooding when parked" problem. 2nd time for me.

Looking inside with a bright light, I noticed bits of metal sticking out where the ON inlet meets the T.  They were still attached and LOOKED like remnants of when the holes were tapped.
I was able to easily break them off with a dental pick, then used canned air and carb cleaner to blast out anything loose.

I couldn't photo the one deep inside, but I did find more of these remnants on the diaphragm side. You can see it in the lower right of the bottom inlet. It's a bit mushed because I already started picking away at it.

It's easy to imagine even the tiniest piece breaking off and causing problems with the petcock.  And obviously would mess up the the carbs once it got in there.

This is more of an FYI post, but as a precaution I think I should install an in-line filter.  I'll dig around on this site for advice, but if anyone has recommendations for a filter I'd be grateful.