Try this
with the radio on unplug the last IF tube (2nd IF ??) then
plug it back in right away. It should make lots of noise. If not
check around the detector tube. If it makes a lot of noise
do the same with the 1st IF.
Tube checkers can lie to you. A tube can be bad & check good. And visa versa.
After that take voltage against the schematic.
73 Zeno
LFOD !