Hi everyone, I received an old Merkur Berlin upright piano as a gift, but it's the absolute best for me! While waiting for the technician (in two weeks), I wanted to satisfy a curiosity, keeping in mind that I have no intention of touching even a single screw; the hammers seem almost "off-axis" relative to the strings; in fact, on keys with three strings, the hammer only hits two of them, while on the bass notes (with two strings), the hammer even plucks the string of the previous note! What could this depend on, and what will the technician do, whom I hope will come soon! Thanks everyone!
They must be centered with respect to the strings. But I am quite sure - I believe Paolo will confirm - given the term you used "old timer", that this instrument needs a general overhaul, IF it is worth it. Let's wait for the expert opinion of pianoexpert.
What Francesco says is correct, except that if the hammers are very marked and in bad condition, as you say, it will be appropriate to replace them. Whatever replacement is made, THE OLD HAMMERS MUST BE RETURNED TO THE OWNER AND PRESERVED. It is important. If it is a grand piano, then THE HAMMERS GLUED ONTO THE OLD SHANKS MUST BE RETURNED AND PRESERVED; that is, the hammers must be replaced, but mounted on new shanks. This makes it possible to avoid tearing the piano's "identity card," meaning being able to see over time if, at most, errors were also made in the choice and mounting of the new hammer group compared to the old one (which should, hopefully, be the original one) (for example, sometimes the striking point line is not "a single line" and has deviations, especially in the high notes, due to the imperfection of the frame casting, which precisely determines the need to "find" the best striking point).
P.S. hammers move over time if they have not been tightened properly with their respective screws and/or if the capstan screws do not tighten well. The piano also has not been maintained over time; otherwise, the problem would have emerged and it would not have been allowed for the hammers to become unevenly marked, generating inappropriate sounds. If two strings are hit, or one in the case of the bass, the sound is significantly distorted. The hammers must be well-centered and their apex must strike the strings simultaneously upon impact. Their travel must be such as not to create abnormal deviations when moving from the resting position to the position of contact with the strings. Sometimes, due to the inclination of the drilling, the hammers describe a certain arc of movement resulting from a mathematical phenomenon. Therefore, one must be careful to glue them with an inclination such that, after describing their travel, they strike the three or two strings simultaneously. Some technicians neglect this principle, which is not easy to apply (and which the manufacturer had probably evaluated), by gluing the hammers incorrectly. The weight, shape, and drilling point, as well as the calculation of the striking point, are also of fundamental importance.
P.P.S. Naturally, the age of the strings and the condition of the soundboard also affect the recovery of sound quality. A look should also be taken at the efficiency of the action mechanism and the keyboard
