Thanks for the JW link. I've been struggling with Tension with my HQ after having it figured out with my Bailey - and he mentions winding them too tight. I had not thought about that - I wound the bobbins for my Bailey on my old Singer 15, but the HQ takes larger bobbins and comes with a winder. I've never used one before, and I'm sure I've got the tension set way too tight for it. I know that as I had to turn it up to 2 before it even had enough torque to overcome the tension.
I had by bobbin tension set correctly - but was finding I had to crank my top tension way down to get it to pull the bobbin thread up to the top - and then it seemed very sporadic.
Looking forward to going home and winding some bobbins and seeing if I can get my problem fixed.