The other thing I am wondering is -- how is the thread feeding? Looking at a photo of a Bernina 820qu, I am thinking that the Glide may feed better if you place it in a jar behind your machine before running it through the threading loop. On my Bernina 1230 (and also for the bobbin winder for my Voyager), I found that I need to use the Superior Threads thread stand to feed Glide thread. Here is a link to the thread stand I use:
http://www.superiorthreads.com/shop/...thread-holder/
(I do not need the thread stand for my Voyager because the thread travels quite a ways straight up before it goes through the first threading loop. I use it only for the separate bobbin winder, and for use in my domestic machine.)