here's a question.. I have a Catatonk Shay that refused to take the flame back to the burner (it had been working fine). A #6 jet installed. Dirty jet? Cleaned the jet, same problem. Borrowed a #20 jet, same problem. Borrowed a #6 from Lady Anne, worked like a champ. Wondering about the difference in the size, I emailed Roundhouse as to the size of the different jets. Harri said they were the same size ("Strange what").