>> But the most dramatic difference you can make in a player action is to
>> thin PVC-e or plastic glue and apply it in every internal area that has
>> suction except the area that a valve will seat, . . .
>
> Pity the next, unfortunate rebuilder who attempts to clean this surface.
> Tried and True (and reworkable) is shellac.
>
> Jon Page

'Amen' to that;  However, I am constantly having to rebuild others'
rebuilds that used PVC-e glue -- it comes off easily if you soak it in
lacquer thinner.

D. L. Bullock   Piano World    St. Louis