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According to Renner USA, the balancier center pin friction is between 6 and 8 grams. On this new set of wippens, the friction is about 1 to 2 grams. Re-pinning is needed. During the procedure, the rep-spring will be in the way, a small hook can be made out of piano wire or a paper clip to pull the spring out of the way. Take one wippen in the same set as sample, push out the center pin and measure its size. The original size is (50-10)/2 =#20. So size #20-1/2 or #21 may be used for replacement. After a few trials, size #21 is going to be used to achieve 6 to 8 grams of friction. A reamer, one size smaller than the new pin size, is used here to just clean the inner surface of the bushing without pushing out any cloth material. The 6-8 grams of friction is on the high side compare to hammer flanges (2-5 grams). To ream the hammer flange center pin bushings, the same size reamer with the new pins is just right. Push in the new pin to connect the balancier and the wippen post, leave pins protruding on both sides, check friction. Clip off the extra length of the center pin on both sides. The clipped surface is like a mushroom locking the pin inside and preventing it from walking out. Now that the reamer size, new pin size, and the procedure are determined, one can remove all balancier center pins and re-pin them all. Pay attention to return the rep-spring all the way back to the slot under the balancier. Check the friction from time to time for consistency and quality control. According to Randy Potter's "G" Piano Works Repair Labor Guide, this process takes up to 4 hours. When finished, return all wippens back to the package, mark the re-pinning date, and store for future use.
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