your HQ bobbin case should have a built in backlash spring. You should not need anything else.
The last time I was having strange tension issues it turned out I had a big lint wad in the space behind the hook assembly (you can see it when the bobbin case is out). I've started using a small vacuum to clean it out during bobbin changes, especially if I'm using cotton thread.
I struggled with tension issues on my Fusion (had Bailey before it) and after a couple of years (and about 40 quilts) I'm finally starting to feel I understand my machine. Half my problem was getting the correct tension on the quilt. I have always floated my tops.
I bought a Towa gauge, and that has been the single biggest step to the success with my LA. Now I just adjust my bobbin tension to 200, and then tweak the top as needed. The second was getting a top tension digital read out. I believe the newer machines come with this now.
Also make sure you are cleaning out under the tension spring on the bobbin case. A business card corner works great, or a paper of similar weight.
Last edited by Macybaby; 12-30-2017 at 11:10 AM.