I have a similar model (TL220QVP-mini) and I can say that the thread cutter feature in the pedal is very, very sensitive. Many times I've experienced what you're describing - I'm only touching the top of the pedal and releasing it but not actually pressing the back of the pedal and it has cut threads (and twice!) I believe my machine came with a rubber insert that can be placed inside the pedal to disengage the thread cutter feature. I've never used the rubber insert but somehow over time I've learned how to manage the sensitive pedal and rarely have it cut unexpectedly anymore. BTW - it's a feature that I would not want to be without now.