I’ve had the tl300 for 15 years and love it but recently I feel like the air slide working properly. It’s slides back and forth but does not seem to control the air intake. I’ve researched diagrams to try to determine where the air control is happening in the stove (without taking it all apart) so I can figure out the issue but I can’t seem to find any diagrams showing it. The closest is the side view in the manual but it really only shows the combustion flow.