BabyLock Proline upper looper thread keeps...

Question

I have used this serger with varying degrees of success for about 5 years. However, this latest problem appears to be unsolvable. After stitching about an inch, the upper looper thread breaks. I've been to our local store and she can't figure it out either. She finally replaced the needles and it worked for about 15 min. Now I still have the same problem of the upper looper thread breaking. The thread breaks somewhere under the presser foot or plate. The thread is loose in the thread-guides that lead to the little pointy arm with the hole in it that moves left and right under the needle plate. This is driving me nuts. I live in rural area. HELP!