Quoted from Chalkey:
The ribbon cable, volume pot, and chip sockets are the most likely culprits. While in the speech test wipe the volume pot from min to max and see if you get anything and give the ribbon cable and roms some wiggling or reseating.
I'm thinking at this point it is the ribbon cable.
Went thought the sound test several times while adjust both volume pots and nothing.
I put new speech roms in and no change (sockets look good, no cracked solder).
Also reflowed the pins for the ribbon cable, still nothing.
I put a lot of pressure on the ribbon cable and got a couple second of speech and then it cut out.
Ordered some new ribbon cable off Amazon tonight and should be here Saturday.
Hopefully that fixes it.