Fanuc Analog AC spindle drive pulse generator circuit?

I have an 80’s Kitamura 300mm pocket HMC with an old Fanuc 6 control. The thing runs pretty good, but recently the spindle will start and then alarm out. I got alarm 2 on the spindle drive “Speed is deviated from the command value due to overload and others”

I followed the Fanuc spindle drive manual troubleshooting and I have something going on with the spindle pulse generator or the drive top board. Need some help.

There are two pairs of signal wires from the spindle pulse generator that should each make a sine wave of a couple volts. Check. Got that at the test pins on the drive. But then the manual says to scope Check pins 7 and 8 and I should see a nice clean .5 to 4.5V 50% square wave. I get that signal on one pin, but on the other I get no signal. I tried adjusting R18 and R19 that the manual says influence that square wave, but no change.

Anyone have a suggestion for components to check/test before I play musical top boards?