This is sort of embarassing but I have to ask...I have an old machine that I love. It's a Singer 15-91 and makes beautiful stitches. The problem is, it has a strange foot pedal. I don't think its a knee pedal, but I could be wrong. It has one "knob" that doesn't do anything and another small "knob" that I'm pushing with my foot. It's very small and on the left side. Am I missing something? I'm so used to pushing the pedal with my right foot, but I have to use the left on this one. What's the deal?