I hope someone can help me or my overlocker is destined for the tip - after days of trying - I cannot get the tension right - I have cleaned it - rethreaded it - changed the needles - tried differrent dial setting - the underneath looks ok but it'got largeloose loops on top which go over the edge any suggestions - PLEASE
Have you tried setting them all that the same setting. I don't have a serger any longer (gave it to my aunt) but when I did I set all the tension dials at the same place...and I think that was at 4. That could be a good starting place. Make sure the other dials (differential feed) are at 0 (I think). And I would test with a couple of layers of woven fabric like cotton or denim. I wouldn't use knits when I'm trying to get it back to normal.
Another suggestion...are you using the same size and brand of thread in all 4 places? Try using different colours, but the same size & type in each of the needles and upper and lower loopers. This will make it easier to see which ones are off. Here is a site I found that may help... http://www.mysecretpocket.com/2007/05/looper-tension-and-cutting-wi...
What i did when I bought my overlocker (it was second hand and had no manual) was thread it up with each spool a different colour. that way when you sew you could see which thread was out and needed adjusting, and adjust the tension accordingly until you get it just right. Otherwise a sewing shop in your area would be able to give it a service for you. No need to throw it away.
When I had my shop and taught sergers, I always taught to release the thread that looked tight first - in your description, that would be the lower looper. Low is loose - High is tight. Remember that. Go to a lower number to loosen the tension. Usually a little bit goes a long way.
Also - ifa thread appears real loose - like you say your upper looper is - check to see it is seated down inbetween the tension discs - I'll bet it is laying on top of the discs, and not getting squeezed. Usually raising the presser foot opens the discs so you can get the thread down in there. Try that first.
Also - thread in this order: Upper looper, Lower Looper, THEN needles -
Hope this helps.