I agree with Ted on the importance of the 100 year servicing by a qualified double gunsmith. And I don't think John Roberts was wrong either. The first part of a physicians Hippocratic Oath is "First- Do no harm." That should apply here as well. Doug Mann's advice to the OP to do a little amateur freshening and refinishing was also probably well intended, and based upon the assumption that everyone is as talented and capable of doing a good and proper job as he is.
Unfortunately, the vast majority of gun owners are not anywhere near that level, and would spend far less allowing a professional to do the work versus the hit in value they would take from improper sanding and refinishing by their own hand. Ted named some double gunsmith's names because simply being a graduate of Billy Bob's Gunsmith Academy isn't enough to be qualified to work on this gun. Anyone who wishes to undertake gun repair and restoration should never start by practicing on a high quality collectible gun. There are plenty of high production machine made guns that would be a much better place to hone their skills and learn.
And no Tea Tree Oil or neatsfoot should be applied to that horn buttplate until after any epoxy repairs to fill worm damage is complete.
