Hi, I ran into this problem on a Brother Serger and if your machine is set-up for four thread overlock, this may help. Set all the tension control knobs to"3". The overlock may seem loose but see if the skipped stitches gets better or worse. Remember that the loopers are just that, they work best when the thread is not pulled tight. I found that if I took the looper tensions back up gradually, I got a pretty nice overlock at about "5" without skipped stiches.