Tension problems can be very frustrating, can't they?? I hesitate to answer because I am not proficient in the use of my megaquilter. I also find that the tension adjustment is not an easy matter.
Please do not "throw the machine out" - they are really a simply built machine and should be "fixable" even if that means a trip to the shop to get the tension adjusted by an expert.
The dealer I consulted on thread usage told me this:
Match the bobbin and top threads as to size and type (cotton, polyester). Do not use dual duty thread, DMC, Tylon, or Trusew threads, this machine doesn't "like" them. However, I was told that cotton or polyester could be used. She said they used cotton Metrosene, and RA cotton. There was Gutterman polyester in the machine when I got it (I got it used.) and that worked well, but I prefer cotton. (I was told by my Bernina dealer NOT to use coats and clark thread in my Bernina or Pfaff machines, so haven't used it in this machine either.)
I've used only size 50 cotton on this machine and so far, it has done fairly well. Double check the bobbin thread is inserted correctly, and check that the top is threaded as in the instructions, it is so easy to get these not quite right. (make sure the thread isn't winding around the spindle, etc.)
Stitch length and speed also seem to vary the tension a little, so try to be consistent with these.
If the thread is being pulled to the top of the quilt, the tension is too tight, and can be loosened by turning the tension knob to the LEFT.
If the thread is pulled to the bottom of the quilt the tension is too loose, and can be tightened by turning the tension knob to the RIGHT.
(My tension knob has numbers on it, but turning it does not seem to change the indicator, so I can't really give you a number for the tension.) The tension may need to be varied with the thickness of the quilt sandwich.
I assume you have the presser foot lever down, as my machine will not start sewing with it in the up position.
The needle threads from left to right on this machine.
This reply is pretty long- winded, but tried to mention all the things I was told about this machine. They can be fun to use when everything is going well, but there are so many variables with these quilting machines. Wishing you luck!!!!