I'm starting to think that this external four-pair cable was for some form of automatic dialer. These often took the tip/ring from the keystrip output as their input. They sent the tip/ring back out to the set's network. What I'd suggest for testing purposes is that you connect the tip of the white/blue to the tip of the white/green pairs temporarily. Do the same thing with the rings of each off those pairs, so you end up basically connecting the white/blue and white/green pairs together. If this restores operation of the phone, at least you'll know what it was and you can move the factory wiring back to the proper terminals by emulating the connection of these pairs at the screw terminals.

Effectively, you want the solid green wires from the key strips to land on terminal F1 along with the blue dial lead. You then want the solid red wires from the key strips to land on terminal 9 along with the blue/white wire from the flash key.

The white/orange pair is likely for A leads, so you can probably disregard it for testing purposes.

That's the easy part. Replacing that cord is another subject.

Ed Vaughn, MBSWWYPBX