The fact that you weren't getting +/-24V on the +/-22V test points on the AR is the main clue you should pursue first. (I think you said you were only getting 17V on one side.)
If I were you, I'd pull the +12V and -5V regulators on the AR, then measure the +/-22V test points again. If they aren't at +/-22V or more (and the same), then the issue is either in the brick, or it's the rectifying diodes or filtering caps on the right side of the AR.
(Actually, you could probably just unplug the J10 connector first, instead of desoldering the regulators. The 36V AC comes in through J9, and leaves as the output voltages on J10, so if you unplug J10, and measure the +/-22V test points, that'll give you the voltages with the load of the game board removed.)
If they are the same, then the issue is somewhere downstream, where either one of the regulators is bad, or something on the game board is drawing too much current, and pulling the supply down. But the first step is to figure out if the issue is upstream (brick) or downstream (game board).