Once, long ago I landed in a house in Poznan, Poland which had the wreck of a Bosendorfer baby grand piano sitting in one of the rooms. I had a lot of time on my hand and tried to figure out the story behind the piano. After tracing the owner it turned out that he was trying to 'restore' the piano but in the process had butchered it and had sent parts all over Poland for refurbishing. For some strange reason the Action was in Gdansk but the hammers were in Warsaw, and the dampers were in yet another location.

I bought the piano and bit by bit collected all the other pieces from wherever they had ended up. What really didn't help is that they had ripped out all of the strings except for the basses, and in the process had scratched the soundboard quite badly.

Over the course of a year I rebuilt it bit by bit with a lot of knowledge gleaned from a local piano tuner, Marek Koczy (he died some years ago). Finally at the end of all that I had a really nice piano, except for one little detail: it had to be tuned up from scratch.

Tuning up a piano from zero is a lot harder than it seems. As the tension on the cast iron frame increases it deforms a bit, enough to de-tune everything you've done up to that point. So the only way to get this done is to tune the whole thing up gradually and to pace yourself so you don't end up overstretching part of the frame or end up in a never ending cycle of de-tunings.

It took me a month, I could probably do it much faster a second time. Never realized that your ears could be tired either, after a couple of hours of tuning I was unable to hear the subtle beats that tell you that you are getting close, very low frequency and soft you need to really pay attention.

Keeping the rest of the piano quiet (especially when it is still a mess) with sympathetic resonances each of which will have their own harmonics is also quite a trick, in the end I used strips of felt woven through the strings that were not 'in scope'.

All in all a fantastic experience and I would be happy to just work on restoring musical instruments. The piano when it was done got donated to the Conservatory of Poznan where it still is in use today, with my lack of skills in play I did not feel that keeping it was right, an instrument like that should be used as much as possible.

edit: HAH! I am so happy. So, the message that Marek had died reached me in a pretty roundabout way through friends from long ago, I did not verify in any way that it was true. So, after writing this little bit above I decided to type his name into google to see if there was an obituary, but instead I found he's alive and well!! https://spsf.pl/pl/marek-koczy/

I will definitely send him a message and maybe go visit, he's one of the nicest people I ever met and had endless patience teaching me all the tricks of the trade.