Increasingly, I am running into a certain category of piano with repetition problems. This problem occurs in vertical pianos, usually 30+ years (although they can be younger), built in Asia with hammer return springs that are held in place by a fabric cord. With time, these cords have become stiff and brittle and are breaking, thus releasing the tension on the hammer return spring. This loss of spring tension reduces the touch-weight of the key and causes the hammer to function erratically reducing repetition and power in the piano. In most cases, this is a relatively easy fix involving replacing the action part on which these cords are mounted.
I recently ran across a Yamaha studio piano about 35 years old in which all 88 of these cords were broken. While the action was in the shop, I took a few pictures to show you just what is involved with this procedure.
So if your thirty year old Asian vertical piano doesn’t have the spunk that it once did, you might want to have me take a look at those hammer return springs.