I have this machine! I don't notice the tension issue until I have to remove a seam and it comes out too easily. I tend to adjust the tension to 5.4 and it works fine. The fix that someone mentioned is at least $200! Way too much after what we paid for the machine. My dealer keeps telling me that the tension is different for each type of fabric or thread or size needle, etc. In my opinion the machine is just too picky and delicate.
Did not know there were bad reviews, wish I had seen them. However, when the tension is balanced it is such a wonderful machine! It has spoiled me for using any other machine! :)
Hope you can get help from your dealer.