Little known secret exclusive to Yamaha pianos: there is a number printed on the top of the action in upright pianos. The first two numbers represent the year of manufacture. For example: this piano is from 1986. https://nostr.build/av/3a440038b07ed1f8f0acc7ce7c76e3d4d3e9c569622c7b9ef1c04ebfb1cf1af3.mov