No help from me. I bunch up the shoulder and neck and start along nicely for about an inch and when I try to change directions I twitch and have points instead of curves, lines cross, the machine gets away from me. I like to hand quilt but seldom do it because I fritter away so much of my day on this infernal computer among other things and hiking with the pooches (mine are: Kit, a field bred Springer who is suffering from PTSD and Rocky, a rescue of undetermined breeding, sort of like a Border Collie with short hair). These 73 year old hands are getting pretty arthritic too. I have a Janome 6600 which doesn't have a stitch regulator but I can set the speed down so that helps if I do my usual death grip on the quilt along with the foot on the floor boards so to speak.
By the way, doesn't Bernina have an after market stitch regulator? I don't know which models it will work on but it would certainly be a great help to you. If one were available for my machine I'd find the money.
Kit's Mamma (she's the Springer named for the black and white snow fox)