Here is briefly the technique:
1. Clean the entire surface with a wet rag.
2. Using denatured alcohol and very fine steel wool, going with the grain, wipe back and forth with pressure to remove as much of the finish as possible.
3. Sand with fine sandpaper in the direction of the grain
4. Clean with tack cloth or soft clean lint free rag
5. Apply Tung oil in the direction of the grain, applying thoroughly but not "wet" on the wood.
6. Wipe it all down thoroughly to remove any excess oil.
That's it. It does take some effort to get the old finish off, but worth it!!