A concert Steinway which had been notorious for stability issues has performed well in a recent festival taking care to "set the pins" although checking and touching up the tuning before the next concert was necessary. This basic technique of finding two stable strings in each note and attending to the one of the three that has slipped will enable people to extend the life of a good tuning and keep the instrument sounding good. Hopefully by watching this video you might be more attuned to listening to and finding the out-of-tune unison and dealing with it.