Hi- my Pfaff Sewing Machine creative 1371 is having some trouble. When I lower the presser foot into the locked position, it does not lock down. The control arm is in the down position, but the presser foot/shank still moves, and does not stay down while sewing. I am in a real bind, trying to finish a quilt for a charity auction that is on Saturday- it is Wednesday. PLEASE help with any suggestions. Thank you! Heather Berger 248-495-3899