OK that looks ok. The clue will be what ac volts you are getting at pin 6 on each IDC 10 pin header on the mac link pcb when separate and when linked measured to 0v while -5dB GR is on each channel. Make sure the switch and threshold settings on both comps are the same.
Ok,
So just and FYI that I was gonna try to fix with you after I got the outputs to match closer. When I have -5 db on both meters the threshold knobs are about a 1/4 of a mark off from each other using the marks on the front panels as a guide. So from one white line to the next they are about a 1/4 of that distance off from each other. Channel A threshold always had to be turned up CW a little more than channel B. This is next on my list to fix but not sure if it can be done.
Here are my measurements for pin 6 on the link pcb. I used the middle pins closest to the switch on each side. Settings are 1:3, GR, and Flat
When both meters say -5DB with the link switch off I get 1.832VAC on Ch A pin 6 and 1.800 on Ch B pin6 . When the link switch is on I get .416vac on ch A pon 6 and .415vac on ch B pin 6.
When I adjust the the thresholds to have equal .855vac on the xlr outputs (same amount of compression on both sides) these are the measurements I get on pin 6. Same settings as before.
Link switch off I get 1.833vac on ch A pin 6 and 1.832vac on ch B pin 6. Link switch on I get .124vac on ch A pin 6and .128vac on ch B pin 6.