I always use a dust mask when sanding any of the older cameras, the last couple I have done the residue actually reminded me of a shellac based glue material or varnish, but I suspect it was a dried out rubber glue solution, I have not found a quick and easy way to do it by hand without using a heavy grit paper that creates heavy scratches in the wood surface...you could probably come up with a solvent that would disolve the residue, but I would suspect that it would penitrate the wood, leaving a base that could be difficult to stain correctly.

Dave