Each programmer contains two circuits: a non-inverting summer and a trigger generator which produces triggers as the CVs on the inputs cross the threshold of the inverters. The main chips are the long obsolete DM7406 which have open collector outputs that are quite suited to the circuit. This circuit is likely easy enough to build with a CMOS 4069 with a few resistor value changes.
There are a number of broken wires and the circuits are looking a bit grotty, most likely the easiest solution will be to rebuild these from scratch.
edit - updated schematic (was missing a resistor)