I don't have the tin lizzie, I have a n HQ 16, and I too float my tops, but always machine baste the top edge of the top. When I first started I had to do one stitch at a time and move slowly across the top, now I can go at the slowest speed. I takes a little practice and a very flatly ironed top to start with.Practice, and you will get comfortable with it. Remember there is no one way to do it.