This is what happens when bass strings are replaced improperly!

The copper winding around each bass string must terminate at an exact point relative to the length of the string and the geometry of the piano. Notice the copper winding in this picture that extends too far, continuing on past the bearing pin, which separates the winding and makes the string nearly untunable. The separated winding also deadens the tone significantly.

Since all pianos are slightly different in measurements, copper-wound bass strings typically have to be custom ordered. This is slightly more time-consuming and costs a few dollars more, but as you can see, it is the only option if you want the job done right.