[Jayce]

Paul, I haven't had issues with 12DT8s on AM and the AM on the Westinghouse is fine, though the chunky rod antenna is very directional. Usually in AM-FM radios the 12AT7 and 12DT8 tubes only handle FM. A case in point is a couple clunker Philcos I have had that played great on AM, but no FM. The reason, both of them had dead FM tubes! One a 12AT7 and the later one a 12DT8. Also I've noticed on Zenith sets that if your FM starts to get weak while AM is good, even with a recap, it's the selenium giving up the ghost. Since the plate is off on the FM tube when on AM, I assume the extra draw on FM zaps the selenium. Sometimes I wish they had just used a rectifier tube!
On some sets the 12BE6 is your AM tube if I recall right.