One overlooked problem of Ampico unit valves and other valves is a
slight warping of the wooden button on which the leather valve facings
are glued.  A very light sanding of the wooden button (sand on a sheet
of glass) before re-facing will correct this, if the button is warped.

In the Model B unit valve, some leakage can occur around the exterior
of the ball bleed.  Over the years the wood expands and contracts
causing the force fit to get loose.  This can be remedied by *very
carefully* reinstalling the ball bleed with shellac, but be very
careful not to get any into the bleed unit or on the ball, or it will
be permanently ruined.

I find the best way to do this, is to remove the ball bleed, and coat
the cavity with a very small drop of shellac, using a very small brush,
let it dry and re-install the ball bleed.  Some suggest complete
replacement of the ball bleed, however I find that over 80% of the
original ball bleeds (That I have checked) to be quite good and tight.
Some will have dirt in them which usually can be removed, by using a
vacuum cleaner and tapping the unit.

Bruce Clark