Damper Underlever Jig and Damper Bean Bag Supporting grand damper underlevers on a rigid, straight fixture during damper installation is the best way to ensure a perfectly even lever height. That in turn allows uniform damper lift with the pedal and the keys, even sostenuto operation, and accurate damper stop rail adjustment. This jig does the job beautifully, with simple knurled brass height adjusters and a clean, functional design. Correct jig height can be set directly from the key end felts, as explained in the included instruction sheet. The jig slips apart into two pieces for easy carrying. Download instructions in pdf format Damper Bean Bag - This item is now sold exclusively by Pianotek Supply Co.  You will get a more even lever height, and less tendency for damper heads to rotate as screws are tightened, by weighting the damper heads when using the Underlever Jig. This seats the felt to the strings, simulating the height that the damper heads will assume once the Underlever Jig is removed and the weight of the levers is pulling down on them. This Damper Bean Bag does the trick. Just lay it on the damper heads, and move it along as you proceed to tighten the top flange screws. A perfect companion to the Damper Underlever Jig above.