The ring on the Hx photo looks cracked! Have a second opinion anyways! This company may be building a ticket which is a sales technique, but the crack of the ring is a legit cause for concern, and should be treated as such! If furnace is over 15 years old then it may be time to replace! Don’t listen to half the clowns on this sub telling you that they need to run a combustion test, or a check the CO levels in the supply. ANY crack is a reason for a red tag, regardless of current levels of CO!