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Needle Inspection
Start by examining the needle for straightness of its shank. One way to check straightness is to hold the needle by the butt, the part that extends out of the groove, so you can sight along its length. Look at a white sheet of paper while pointing the needle at the white surface. A bent needle may stick in the groove or effectively change the timing for that needle.
Timing of the cylinder needles is not usually considered, because it is fixed by the rigid mounting of the yarn carrier. However, timing of a cylinder needle may be slightly off if the carrier post is bent to the right or left or the needle is bent slightly right or left.
Next, check the alignment of the latch. The latch must touch the center of the hook when it closes. Bend the latch if necessary to line it up with the hook. The latch may be ruined by bending it straight, because the bending may cause the latch to bind in the closed or open position. Add a drop of oil to the latch joint and work it to see if it feels loose. If it feels loose, you are ready for the next test.
Make a two ounce weighted object and tie a small loop of yarn to the weight. Use the type of yarn that fits the machine in use. Ten quarters in a plastic zip-lock bag will be two ounces. Then fold a square piece of paper on a diagonal and tape it on a wall near by so the diagonal is at a 45 degree angle.
Hold a needle up side down and hang the weight on the hook. Close the latch on the yarn loop firmly with your fingers. Rotate the needle, keeping the latch on the upper side, until the yarn begins to slide down the needle toward the latch. While rotating the needle, hold it in line with the 45 degree angle prepared for this purpose. A good needle will let the yarn slide down and open the latch before the needle was at a 45 degree angle. Rotate the needle a little more until the latch itself is at the 45 degree angle. Yarn should slip off the latch by the time the latch is parallel to the 45 degree slope. Now reverse the rotation of the needle so the yarn loop slides back under the latch and closes it. Use the 45 degree reference angle. This time the loop must fall off the needle before the angle of the latch reaches the 45 degrees. This test will confirm that the latch is free and that the needle surface is smooth enough to operate properly in the machine.
If the latch opens easily but the yarn does not slide easily in both directions, the surface of the needle needs cleaning. As mentioned before, a rusty needle would have been recognized as rusty. A needle may look OK but have a thin surface residue that is tacky to yarn. First try a cleaning solvent and nylon scrubber pad. Repeat the test described above. If the needle still fails the test, this is where 400 grit sand paper is useful. Small pieces of sand paper can be folded over the needle and rubbed on the hook and latch, inside and out where yarn contacts the needle. When these steps are followed, an old needle can be restored to work like new. In the process, be prepared to throw away a few of the needles. Some will be worn or rusted beyond the point where it is practical to repair. It is easy to spend ten minutes or more on an old needle to find it was beyond repair.
These instructions are given to help the csm hobbyist recognize a bad needle as well as how to fix one. If new needles are available a choice can be made between buying new or repairing. There are times when new
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