Someone else may have already said this (I haven't read all the answers yet). Pfaff has an accessory threader meant for the serger, but it works for ANY sewing machine. I bought an extra, so I have 1 for AZ and 1 for CT. The wire thingy on Pfaff's built-in threader can get bent, and then it won't thread unless you push it back in place, and it WILL eventually break if you have to do that. That's why I use the little accessory. It works for ALL weights of thread and ALL needle sizes.