Johnson Ranger VFO advice please

[Leslie Zwiebel]

    I'd appreciate hints re a problem w/ my Ranger on AM:
    QSO reports on 3.870 are that FSK-like activity is heard behind my
decent power/decent audio signal, as if I am also sending a RTTY signal
concurrently!
    I can hear it myself when I "Zero" in the shack using the Ranger in
order to spot the net frequency I am hearing on my receiver.
    On-air front panel metering shows no probs.
    Helpful local AM'ers have suggested, and we have tried the
following: inserting a crystal and running rock-bound, which eliminates
the problem, pointing to the VFO as culprit.
    It does not occur (signal is clean) on 40M(!), so we are thinking
about components in the 160M/80M/ loop.
    Two or three substitutes for the 6AU6 in the VFO are no help. Will
also try a sub for the OA2 VR tube. Poking around at solder joints and
grounds, at least the visible ones with the VFO cover off has not
yielded any change.
    Will probably next start VOM measurements on top layer of the VFO
compartment.
    Before we start taking off the panel to access further layers of the
VFO (alot of work), I'd appreciate any ideas.
    (((((73)))))
    Les
    Menlo Park, CA