In Digest 1971017 Darrell Clarked asked:

> ...the bass notes tend to drop out sooner than the treble
> side, apart from the unevenness due to other problems (valves and piano
> action).

A possibility is that there is too much friction in the bass section.
Check the down weight with an accurate set of gram weights. Ideally,
the down weight should be in the low 50's, with the difference between
bass and treble being only a few grams. The way I measure down weight
is to set the weights on the key, press the damper pedal ( to get the
dampers out of the loop), and then wrap with my fist on the underside
of the key bed. The key should fall gently to let-off. If it falls
quickly, subtract weight; too slowly, add more weight.

Another possibility is that the piano action distances have changed,
possibly due to brackets made of pot metal. Distances are very critical
and exact. If they are not right, the various parts do too much sliding
and not enough lifting. The results are friction, wear, and especially,
a heavy touch.

One more possibility is that the bass end of the player stack is too
low. If there is lost motion, then it takes more force to make it play.
The symptoms are as you describe.

       Jeff Davis