Hi Will. I agree that it is a good idea to consider adding plate bushings in cases where there were no bushings in the original design. There are many things to take into consideration, but today, I would never design a piano without them. My experience in manufacturing has been with Baldwin and Mason & Hamlin, but my experience in rebuilding has been more with Steinway than either of the afore mentioned. I remember that I was shocked to find the impression of the tuning pin threads in the holes in the plate in a rebuilding project, many years ago. That piano was a Steinway, not to say that it might be more common in other pianos. As I said, most of my rebuilding experience was with Steinways. In any case, when I took note of certain tuning pins that had a serious tic-tic-tic problem, I discovered that after removing the pins, these were the very ones that revealed a clear impression of the tuning pin threads in the cast iron surface within the holes in the plate. Regarding plate bushings, many manufacturers will say that they serve only one purpose, to center the drill in the hole. I would say they serve a more important purpose, to prevent direct metal-to-metal contact between the tuning pin and the plate. But, it does serve to center the drill bit. I would prefer to center the drill bit at the BOTTOM of the hole in the plate, but plate bushings center the bit at the TOP of the plate hole. With modern CNC machines the drilling can be centered on the bottom of the hole, regardless of the center hole of the bushing. Frank Emerson
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