Eliminating AC hum problems?

[jpdylon]

I got a Setchell Carlson from Adam not too long ago that has a power supply issue. The B+ is about 38-40 volts lower than expected. It is accompanied by alot of ac hum, both in the picture and in the sound, and also making the picture difficult to vertical sync. I think the hum may be part of the problem.

The power supply secondary for the B voltage passes through two small diodes (no tube LV rect. here) and then goes through a dropping resistor (which reads the correct impedance) before going to the filters. If I bypass the dropping resistor the B+ is close to normal, but the hum gets worse.

The entire set has been re-capped. I've heard that a H-K short in a tube can cause hum in the picture and sound, but I'm thinking not to this extent. I'll be gettting a sams for it soon. Does anybody have any suggestions to eliminate this nasty problem? Different rectifiers?