Hi Al,  here's my take on your Stella issue.  First, the comb(s) and
dampers _must_ be completely dry.  Since the sound is produced by the
comb(s) and you mention they are covered with lubricant your first step
to getting the sound improved would be to remove the comb(s) and then
remove that lubricant.  This is likely the cause of your weak sound.
In fact, I'm surprised you have sound at all based on your description
:)  Same thing with the dampers.

Regarding your split sound board, one of my Mira 15-1/2-inch musical
boxes has a split with slight separation completely down the middle.
On each side of the split I have positioned each of two original
adjustable sound posts (that connect the underside of the bedplate
with the sound board).  The sound produced by this box with the sound
board split is absolutely superb.  And the volume produced by this box
is incredible.  I own three of the 15-1/2-inch Mira boxes and this one
beats them all for overall sound and volume.

Now, granted, this is a Mira, not a Stella so you may have done the
right thing in repairing your sound board but in my case I would never
touch this seemingly odd aspect of the box.  In summary, you will need
to get the comb(s) out and carefully clean the lubricant out of them.
Also make certain to carefully clean in between each tooth and its
associated lead.  The teeth and leads must be nice and dry and be able
to vibrate freely until their associated damper (for the teeth that
require a damper) quiets them.

If you do not feel comfortable doing this yourself without damaging
something you should seriously consider sending the movement to one
of the reputable music box repair professionals.  That's my take from
a collector's point of view.  Good Luck.

Doug Olds