I thought the balls were plastic, not steel?
When I sent my Model A to Greg Fuller for some work on the safety and lever pin (protruding and bent so couldn't pump the gun), I wanted him to go thru the valve and replace the internals, etc., thinking of it like a streak. He suggested we see if it pumps and holds first, and if it did, then don't do any valve work. Seemed odd at the time, but makes more sense looking at these drawings.
Pacific Airgun Expo