OK, so it's not forming stitches - is your needle inserted and barely rotated just slightly left or right? You don't want it perfectly at 6 o'clock. I use 6:30, some use 5:30.
Also maybe lower the hopping foot just a scootch if there's much of a gap between the foot and the quilt top.
It sounds like the upper thread is being pulled just a little when you're pushing the machine to the back.