No woodwind will play well unless the pads cover the tone hole sockets perfectly. Leaking tone hole sockets are the cause of squeaks and squawks, windy and hard blowing tones. Detecting leaks and correcting them are important duties of the saxophone player.
One way of detecting a leak is to close all tone holes and the bell and fill the instrument with smoke. A wisp of smoke indicates a leak. Leaks’ can also be located with a little gadget called a “feeler.” This is made by cementing a narrow strip of Cellophone to a match stick. Slip this “feeler” between the pad and the socket edge and close the pad with the key; then gently pull the feeler out. By repeating this process all around the edge of the socket, you will notice varying tension on the feeler. Where there is little or no tension on the feeler when it is pulled out, there is liable to be a leak.
A more elaborate equipment for locating leaks is a small light bulb on the end of an electric cord. Electricity can be furnished by installing a transformer on the regular house electric circuit or by a flashlight battery. This light is lowered into the saxophone. When the keys are closed, light showing between the pad and the socket indicates a leak.