Here are the things I have tried:

1) examined the RIT circuit to make sure it was not
pulling the VFO

2) replaced the zener diode in the VFO power input with
a three-legged voltage regulator. (my schematic says
something like +6.8 but the measured voltage was about
double of that. I believe I ended up putting a 12 volt
regulator in there.)

3) replaced the 10pf capacitor between pin 1 of V-3 and
ground. (this had the most positive effect)

Chris