DW6000 repair

[Lamster]

Hi Just aquired a DW6000 for free.
After downloading the service manual and some initial checks
only 4 of the 6 voices are functioning.
The manual explains about needing a voice ID card which i've got around by using a scope. The problem manifests on voices 4 and 5 one being high frequency and the other appears dead I initially decided to swap the NJM2069s the fault didn't move so its not them just as well as they're expensive when you can find them..
Tracing Back Further the signals are incorrect from the adjacent digital board.
There appears to be some switching through some 4066s fed from IC 14 and 15 from 2 74ls138s can't really tell whats going on there.
So some advice would be helpful
Cheers