Machine Quilting. I have a one-year old Pfaff Quilting machine. I am running into two problems

Question

I have a one-year old Pfaff Quilting machine. I am running into two problems while quilting: when using free-motion quilting -- which is so much fun to do -- the machine skips stitches, especially when moving the quilt sandwich towards me rather than away from me. The needle thread just won't catch the bobbin. The second problem is the needle thread shreds into little balls that get caught up in the tension goomer then break. I think I need a bigger or different needle. But I've gone up and down the needles from 60 to 90, microtex to universal to topstitch. Is there one right preferred size or style of needle that improves this problem? Thanks. Susan