Sometimes dampers wobble as the key is pressed, especially on a hard blow, and can actually produce an audible vibration (a strange and annoying sound). Dampers with extended wires (usually at tenor/bass breaks) are particularly prone to this.

There are 2 remedies:

1 Replacing the wire guide felt.

2 Cutting back the damper head and re-cranking the damper wire (so that the damper head protrudes less, and so vibrates less).

Usually, both remedies are required – though as you can see from the pictures, only a 1.5mm thick sliver had to be removed, and the head sits just that amount closer to the plate arm…and now doesn’t vibrate!

Showing cut sliver (protruding)

The newly cranked wire

First bass damper now closer