Kind of odd the things that people disconnect.... I wonder if someone had changed the rubber in the past and the switches got locked on and this was their solution? (Common issue with the rubber that new owners don't catch).
The return wires are the brown-green-green ones on the left in your pic, they get connected to the blade of the standup 10 pt switches that does not have the diode on it.
The strobe wires are the black-brown-brown ones, these go to the banded end of the diode on the standup switch. On the plus side, since they are the same you could just twist them together if you don't have the standups, and your extra ball target should work. (It's likely not working because the wiring chain is broken here.)