Wooden wheels off prairie schooners, old doors from western saloons and even wooden rocking chairs from the last century all have the same problem. The structure of the wood has declined to a point as to become structurally questionable. But you can halt the process. If the wood has taken on a gray, weathered look, don't try to make it look new again. Preserve what's left for the next century by using deep penetrating oil on the antique wood.
Place the wooden antique in an open area where fumes won't be a problem. Using the blower attachment on the air compressor, get in close and blow all the dirt, loose pieces of wood, debris and any other loose material from the wood.
Scrape the wood gently with the wire brush, getting in the corners, finding any loose splinters, chips, etc. Spray down again with the air nozzle.
Pry up any loose splinters or chips with the utility knife and force glue into the crack. Close the crack and hold in place with masking tape for one hour. Scrape off any old paint, shellac or lacquer with the putty knife; take care not to remove any wood.
Using the screwdrivers, tighten any screws, plates or parts that have come loose.
Fill the paint sprayer with the boiled linseed oil. Spray the wood, completely saturating it. Make sure to get into all the corners and underneath sections. Wait an hour and spray again. Let dry overnight. Spray the wood again the next day until the oil begins to pool in the recesses and cracks and the wood will not absorb any more oil.