Here is how I bench-tested mine.
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30086924/srt/pa/pging/1/page/2.cfmOn page 1 of that is a photo where it shows my clamp to cover more of the air holes where the slider did not move far enough because of its screw holder.
I was getting too much air. If you get it just right the flame looks better and it sounds better--not so noisy.
In a previous episode, the whole burner was rusty and the little flame spreader cap broke off, which made the flame look bad. I got a new burner as seen in that photo. (amazon has them) The OP here says his burner is ok though.