All my machines have a knob straight up from the presser foot, on top of machine. When there is too much pressure on the foot I must turn it to take off some pressure. When I FMQ I must take all pressure off the foot, I also have to lower the feeddogs. So I loosen it as much as I can. I have a little window - dead straight in front of me and I can watch it go up to top of the machine as I turn it. When I am done I turn knob opposite way to tighten it so feeddogs will pull the fabric throught.