Singer Quantumlock 14T957DC Detailed Threading Manual page 42

Using the tweezers thread the next 4 guides identified with a small brown dot.
Using the tweezers thread the last thread guide that is located on the left just
below the looper. Next thread the brown looper eye from front to back, pulling
the thread over the top of the red looper, then pull the thread tail to the back of
the serger approximately 4 to 6 inches. Make sure the thread sits over the top
of the V cut out just before the eye of the looper. (See page 21 illustration 10 of
your manual.)