Well as I have my PC Scope back I can try a few "Programs" and display the output on the scope. I have now tried several "Programs". So first use the two new Pots to add voltages. Plug the system so the +10v Reference goes to the top of the calibrated pots and the wiper goes to one of the amplifiers. So the input can be read off the pot. Here is the wiring:-
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Here are the pots set to 5 and 3...
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Here is the output. It should be "8" but the reference voltages are a bit low.
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Also note its "-8" as the adder inverts.