Paper caps all replaced, and a couple out-of-tolerance cathode resistors
swapped out for 1 watt carbon film. The 6F6 output stage cathode bypass
electrolytic was also replaced; it wasn't in the can as specified in the
schematic but was a "Dandee" brand 10uF axial lead type air-wired inside
the chassis.

The paper caps were a hodge-podge of different brands - Mallory,
Aerovox, Sprague, Tobe Detustchmann. The can electrolytic is an 8uF/8uF
unit instead of the specified 6-6-6. Some of the paper caps weren't the
correct values e.g. the 0.25uF paper cap was actually a (very large)
0.5uF unit. I'm guessing the last time this radio was serviced might
have been during WW2 and perhaps wartime rationing had something to do
with it - repair shop made use of whatever they had on hand.

Maybe surprisingly both sections of the can electrolytic reformed OK
running a current thru it via stepping up the voltage ranges while on
the "leakage" setting of my Heathkit IT-11. It took about a minute for
the eye to open at the rated max voltage of 450. I measure a "power
factor" of around 3-4% on both sections at that voltage. Don't know if
it would be good to leave that as is but I'm using it in-place for testing.

The 5Z4 and 6F6 + power supply circuit seems to be working fine, with
the set powered up the voltage on the first capacitor section and the
second after the field coil choke look approximately correct.
Injecting1kHz into the 6F6 grid and into the grid of the 6J7 detector I
get a strong output through the speaker with no hum.

The problem now is that the plate and screen voltages on the 6A8 and 6K7
are way off; the service manual specifies 195 and 210 for plate voltages
respectively but I'm actually getting more like 260 and 275. The screen
voltages are specified as being 70 and 90 respectively but I'm looking
at about 130 for both of them. Pin 5 of the 6A8 looks correct at about
-10.5 volts. Cathode resistors and bypasses were replaced on both of
them but the cathode voltages are high, e.g. with the AM broadcast band
selected, volume all the way up I'm reading about 4.8 volts on the
cathode of the 6A8 instead of 3.

With a 3 meter longwire antenna I'm getting one local strong AM station
(50kW about 8 miles down the road) at night but the AM band is otherwise
silent. I'm guessing at this point one or both of the 6A8/6K7 has poor
emission? I don't own a vintage tube tester but I have both HV and low
voltage bench supplies available, any suggestion on how to rig up a
quick emissions test?