I've found that tension issues are mostly solved through the process of elimination.
Some things to check would be to use the same weight of thread in the top as in the bobbin, unless you're quilting with .004 invisible nylon thread. Nylon is not recommended for use in a bobbin.
Also, make sure the size needle you're using is compatible with the weight of thread you're quilting with. Example: If you have a very fine thread passing through a size 90 needle, that could be tripping you up.
Try checking the tension on your bobbin. Most bobbin cases have a little screw you turn like you would if you were setting the hands on a clock. Reset both your top and bobbin tension back to normal and see what happens when you adjust the screw, making note of where you start, e.g., 2:00.
Also, make sure the top thread is firmly in place between the tension discs--threading errors are often to blame for tension problems.
And finally, check to make sure there's not an excessive amount of lint inside your machine.
The only other thing I can think of is to make certain the quilt is fully supported behind the machine, to the left of the machine as well as the portion in front of the needle. The quilt's weight can pull and cause stress on the portion that is trying to pass under the needle.
Good luck to you!