I bought a Thermador PCS484GD cooktop about 16 years ago. It burns LP - not natural gas. Ever since we purchased the item, there has been black, sticky soot on the bottom of the pots (all 6 burners affected) after cooking. It was my first gas stove, so I thought it was normal.

Recently, I bought a new 6 burner Thermador (also LP) and immediately noticed that there was no soot on the pots.

Now, I realize that something is wrong with the original unit. I have read about low air flow to the unit as a potential cause, but do not know how to check that or adjust.

Is there a simple fix?

Thanks in advance for any help offered.