I just wanted to tell the world. A few weeks ago I repaired a piano. The coop inherited it (Thanks Matthew) and a bunch of people moved it through a hedge (Thanks Justin) and up 6 large stairs through a narrow hallway (Thanks Rob and everyone else).
It had four broken keys, and a little baggie with three broken hammers). The guy at the Music School's piano-tuning workshop, who lent us equipment for the move, also told me how to repair those three hammers. He even had a mock up of a key.
Behind your piano's panels, between the ivory-wrapped wood and the string, are 43 parts, levels, wedges, pulleys. Wood, felt, wire, string, spring and leather. Picture. So much to go wrong. He made it sound so easy. I spent the day, taking apart the piano and putting it back together again.
The way to mend a broken hammer is to get some thread, cover everything in glue, reattach the two pieces, and wrap the whole length of the hammer's fracture tightly, around and around, with the thread. Get the thread real goopy and let everything dry. The thread is tight enough that you don't need a clamp or anything and you reinstall the hammer with the thread glued on.
There are still a few stuck keys; that has to do with this tricky felt/wood, bouncy bit called the hammer butt. It also hasn't been tuned since 1973. Of course, before I can fix that I have to learn to hear the difference between major and minor.