I have just purchased a Schulze & Pollmann upright from '52 - '53 that has been very well maintained and, above all, used very little. Contrary to what I feared, the piano is out of tune but it already seems to be in tone to me, though the tuner will tell me after the first tuning. By the way, do you know anyone very good in the Como area?
Two keys do not return; I think it's the friction of the escapement on the capstan, should graphite be used for lubrication or is a little cleaning enough?
In the video tutorial, I didn't quite understand how to adjust the hammer alignment and the centering of the strike on the strings.
One last thing, how do you restore the cracked lacquer on the cabinet?
Regarding lacquering, I cannot suggest anything to you. There are Kits... but they are difficult to use and without perfect results. Polyester polishing can "break" like glass because it has considerable thickness.
Regarding hardness, you suggest a non-return of two keys which tells us that this may depend precisely on the excessive friction of the center pins. Perhaps. Tuning, regulation, and hammer voicing. Then check the let-down weight and the return weight of each key: if the let-down weight is high (55-60 gr +) and the return weight is very low (-20 gr.), then there is an impediment due to excessive pin friction. Otherwise, the let-down weight may be "somewhat high," but accompanied by a good return weight. Then it is acceptable. Without a decent proportion between the two values (such as a ratio of about 2.5 gr.), smoothness and repetition are not guaranteed
I checked the escapement weight: 55 grams. What would be the minimum escapement weight for an upright piano? The other piano has a very soft keyboard but certainly not suitable for classical music; the Schulze I currently possess is not so soft, but it's not like the Petrof I had about ten years ago which was rock-solid. The two keys that are not working are the escapements that do not return to position. The springs are there, so is it the pins that prevent the escapement from sliding along the axis? How can I unstick them? No one has played this piano for at least 20 years, and before that, almost no one played it.
It could be precisely because of inactivity. Play it, and if you reach the point of touching the escapement lever, give it a "massage" to warm up the pivot. Some technicians partially remove the pivot and physically heat it with a flame. I am against this: in fact, the heat warms and expands the pivot which, upon cooling, flows better... but this expands the wooden hole of the central part. This part must hold the pivot very tightly so as not to let it slip out of its seat with continuous movement. "Massaging" up and down only warms the part in contact with the felt-lined holes. There will be an improvement, which however could also be temporary. If it recurs, the defective pivots must be changed. On the occasion, others should also be checked as a sample.
