Greg looks like you have all the parts you need to have the coin return work, do they all move freely? is the linkage on the mech move up and down? that screw on the linkage that you are pointing to is to adjust the linkage to operate properly.
I would start with the escalator, if you lift and lower that linkage will the coin return out of the side?
Next I would with the front casting removed and all the mints out of the side with the linkage, try and push that lever in and out and look to see how it reacts with the linkage on the mech and the linkage on the escalator, you may only need to make some adjustments.
Try that and lets see how you make out,
Al