Freezer at 20, Reefer at 60

This a Dometic RM2652. I cleaned the burner, was't much there hardly any rust and nothing came out when I tapped on the flue. Lights up right away and stays lit. I get the same result from propane and 110v. It seems to me that it has been going this way just recently.I What am I missing here? It looks clean behind the access panel, nothing obvious bent, broken, burned or appears to leak. Looked at a bunch of youtube videos and didn't get much except a cooling unit replacement which might be out of my wheelhouse.
Thanks.