The threader is made from incredibly thin wire - and therein lies the rub! The wire tends to bend, to curve, to become totally useless after a certain amount of use. I have discovered that using the thicker thread that I'm using for my current work makes a needle threader buckle under the pressure.
Anyone who 'punches' will agree that the most interruptive part of the job is threading the needle. I purposely cut very long lengths of thread -- of course then I often have the problem of the thread tangling but nothing is perfect *smile*.
I have just received 12 threaders -- hopefully that will last me for awhile...
"Laughter and tears are both responses to frustration and exhaustion. I myself prefer to laugh, since there is less cleaning up to do afterward." - Kurt Vonnegut