I cant see the schematic, too small & blurry. Also it is
laid out messy. Give a point to Sams for drawing all
schematics the same & with sense.
If something is loading down a source & the dropping
resistor is the right watts it should get real hot fast.
Measure ohms to GND from the source. If it reads say
5K look for anything that is fed with about 5K resistor.
Example if a 4.7K feeds the G-3 of a tube there is usually
a decoupling cap to ground that may short. Pulling
any tube using the source is another test.
Another place I found a few times was the tuner B+
feed-through shorted.
Good luck
73 Zeno
