I've looked at other posts about the PRV so sorry if I've missed the answer to my question / query, which is:
Among other things I ordered and received a new ball and spring for the PRV. The existing spring is comparable in size to the new one, but the ball I removed is about twice the diameter of the new one, which I would think affects the operational efficiency of the valve. I'm inclined to fit the new, smaller ball, but before I do, any comment or advice would be much appreciated.