Fleetwood 2002 - SW works, hum & no reception on AM.

[VintagePC]

I have a fleetwood model 2002 SW/AM/Phono radio which is almost functional. I get a loud hum (it does change when I adjust the dial) when on AM and can't find any stations... but shortwave works with no hum at all.

The schematic is here:
http://vintagepc.site50.net/site/fle.../RADIO_006.png

The way it's wired up, it looks like if SW is working, then it means the tubes are functional.. I have checked basic stuff like continuity but I'm not above checking it again if someone thinks there might be an open coil or so somewhere.

Have not tried an alignment yet; but I'm unsure whether that's the culprit or not; there aren't any caps in the broadcast section that were paper; all those I've changed are shared between the two.

Hopefully someone here can help me with this, it's got me stumped but is probably something the more intimate of the radio techs here can diagnose by smell or something