Little by little I'm learning the very simple works of my Harmonium
paper roll layer and yesterday found that the doughnut shaped leather
parts in the bellow valves were dry and partially stuck to the metal
housings.  I carefully removed the three tacks from each metal housing
plate, separated the leather rings where they stuck to the metal, then
carefully sanded the internal metal surface smooth where it contacts
the leather.  The actual leather rings were very dry and did not seal
properly.

Since I will eventually replace these leather valves anyway I decided
to soften them up with a light oil so they would seal better when they
open and close with the bellows movement.  They work much better now and
the player creates much more vacuum and volume.  For future reference,
are these leather pieces supposed to be softened with some type of oil,
or is what I did considered the wrong approach in the long run?
Thanks.

Michael Pawelek