Bleeding Federal Power Steering pump

Resevoir was leaking on my 71 340 Dart with Federal pump. Power steering worked fine. It was just leaking. Removed pump and replaced large Oring around the housing to fix the leak and the seal on the back where the bolt goes thru. Also replaced the return line but not the pressure line. Reinstalled, filled with F type ATF to the bottom of the neck. Jacked up the front of the car and worked the wheel back and forth a good 30-40 times at idle and couldn't get the fluid to drop. I even took for a short drive but no luck. I'm guessing the box itself went dry while pump was out but not sure how to get it to prime again.

Tips or ideas???,