If the joints are stuck, the wood has extended. Make sure you take your tool to a certified repairperson directly to unravel these problems before cracking occurs. One of essentially the most common questions I receive regarding upkeep is even if the bores of wood bodied instruments could be oiled. There is no simple answer. I have never oiled my clarinet bores, and I have never had a crack. However, some people have a body chemistry that causes the clarinet bore to dry out significantly. If your instrument has a very dry bore, it is a good suggestion to oil it. Do this only during cold months when your heating system dries the air or if you live in a very dry local weather. To oil the bore, place a few drops of bore oil on an old swab and pull the swab throughout the tool. The critical thing is if you do it once, it's a must to then do it continually — once every two weeks or so in the course of the winter months in cold climates, or more often in very dry climates. Do not use the rest other than the bore oil you find in music stores, which is formulated from light mineral oils that will not turn rancid.