Well Hank, I checked Quincy's literature library again and the oldest ROC for the 212 is still ROC 25, so it appears they haven't found any additional info for the ROC 17. On the later ROC model, the oil pump is located where your hydraulic unloader is and the unloader is around the corner on the right side. Take a look at the Binks ad, which shows the correct plumbing layout...receiver pressure to bottom of hydraulic unloader, top of hydraulic unloader to unloader tower.
The idea is that when the motor starts, until the hydraulic unloader sees oil pressure, which opens and closes a valve allowing receiver air pressure to the unloader towers the pump will not begin to make pressure. This action has 2 benefits, first, it allows the motor to start without a load, second, it allows the pump to have oil pressure before loading it.
I would have to guess that the hydraulic unloader has failed to function (due to worn internals) and was just bypassed.
The current single stage QR Quincy's only show 100 PSI as the maximum CONTINUOUS operating pressure, and a couple of models (108, 206 & 210) with a maximum INTERMITTENT operating pressure of 150 PSI. Does the Binks ad have any info regarding pressure rating?