I was bumbling along looking for help with my Tin Lizzie 18 sit down machine. HELP...

. I have owned this machine, it's fine but I just can't seem to get it to stitch backwards without producing loopies on the top most of the time. It's not consistent and I've tried everything I can think of. I did go on the Lizzie website and couldn't find help there. Does anyone have any helpful hints? I am trying feathers for the first time. I need to have that backward stitch work right.