This document summarizes the process for replacing hammer butt return springs on an 1880s Bechstein upright piano. It describes removing the broken spring from the hammer butt by prying it out with tweezers. Then, a replacement spring of suitable size is selected and its long tail is fed through two holes in the hammer butt and pulled firmly through. Finally, the excess length of the tail is clipped off and the spring is flattened against the side of the hammer butt.