The damper regulating screw, also known as the damper screw, is a long flathead/hex screw on the rear side of the whip in a Wurlitzer piano action. Each note has an individual action mechanism that includes this screw. It forms part of the whip assembly. Threaded through the screw is the damper grommet which connects the whip assembly to the damper arm.
Function:
The damper screw connects to the damper rod, also known as a sticker. When a note is played the key raises the front of the whip. Pivoting through the whip flange the rear of the whip is lowered. This pulls the sticker and the damper screw down, which in turn pulls the damper arm down. Pivoting through the damper flange, this then lifts up the damper felt causing the feed to sustain.
The damper regulating screw is a crucial part of the Wurlitzer action, and one of the three action regulation processes. The other two are key lost-motion and let-off adjustments. Incorrect damper regulation can lead to notes not sustaining when the key is played, or continuous sustain meaning the damper is not working. These can be some of the most notable problems that affect the action.
Servicing:
The correct regulation for the damper screw is 0.035” or 1mm above the smaller grommet, though more is acceptable. Increasing the amount of lost-motion here can make the touch of the key feel somewhat lighter. The primary concern is for notes to not continue sustaining when the key is released, and for evenness throughout the piano.
The damper screw can be adjusted using a small flathead screwdriver, or a 7/16” nut driver.
