Use a needle oiler, and take care that no oil comes into contact with the plastic body of a pupil tool. Check to see that the screws are in place and have not twisted themselves out of the post. Lost screws will mean lost keys. If the screw is too far out, tighten it with a small screwdriver until it is level with the post, but do not overwind the screw, as the key may bind. If in doubt, seek out a qualified repair person to fix, maintain and adjust screw tensions. Wooden clarinets are often subject to cracking, a condition we all hope to bypass. Cracking can occur if a part of the wood absorbs moisture and expands while other sections are too dry; the difference in pressure may cause a crack. The same can be said of temperature. If you blow
hot air through a cold instrument, the temperature difference may cause the bore to expand while the external
remains cold and gotten smaller. Either way, the force on the wood is inconsistent, and cracking is possible. For this reason, never use a wooden device on the marching field.