One of the loopers on my serger, the one closest to the body of the serger, was loose and wobbling around like a child's loose tooth. I got the screw tightened but it still would not stitch.
After that, I kept putting it off, thinking I would rather take my serger to my sewing machine mechanic than try to do it myself.
Anyway, today, (soon to be yesterday) I decided I needed my serger and could do it myself. I got out my allen wrench kit and tried different wrenches until I found the right size - it took a size 2 - metric.
I could not get that little screw to turn so I got help to loosen the screw. Then, I just slowly worked the hand crank so I could watch the positioning of the looper as it passed the needle.
When it hit the sweet spot, I tightened the screw with the size 2 allen wrench and rethreaded the beast. It stitched perfectly, and I saved the cost of a trip to the sewing machine repairman and a week without my machine.
The serger in the picture is not mine - it's a MorgueFile picture.