> ... we are not getting enough sustain on the high notes ...  I would
> also welcome any information on a dampening system for the low notes.

To get sustain from high notes you must have very rigid mounting to
drive the comb "body" to a very high frequency.  For tuning, to
lower the frequency of the note, I would add material at the tip end
or thin at the base of the tooth.  The sharpen (raise) the frequency
I would remove material towards the outboard end of tooth to sharpen.
The center gets cut when getting the entire tooth thickness set.

For damping you could place an elastomer material under the tooth
tip (this would make note somewhat "self damping" plus quiet note
pickup) or perhaps a "ramp" (very hard rubber, Teflon, or similar)
ahead of each base note pin could work well.

A note on what I'm up to -- I have been working at a bio medical
company developing a really tiny blood analyzer, and I have remarried
to a very lovely lady.  We have our web site up again and plan to put
lots more mechanical music things there, including some items people
have asked me about, but always seem to get lost in the shuffle.

I also plan to resume restoration work, so please let us know of any
needs you have.

Thanks,
Alan & Mary Erb
http://www.mechanicalmusicbox.com/