Those new burners look great. I discovered something that I thought may have contributed to your previous problem. I built a new burner last week, and when I was going through my fittings I spotted my old fitting and a brand new one that attach to the propane tank. They both had a built in restriction, a .020 or so orifice. The fitting I now use has a through hole about 5/16" dia.. I believe if a person was using a fitting with the tiny hole but a larger orifice on the burner you could have all kinds of trouble leading to a real finicky burner. I think the ones with a small hole are for Bbqs, the one I have with the larger hole came with my regulator.
It's something to look at, and keep in mind.
Again, good job on those burners!
Alden