I called Customer Service because I was having trouble with the upper blade holder. The person I talked to was knowledgeable and very helpful. I reasoned that the spring in my Pegas blade holder was causing the tension arm to pop loose during cutting, so I ordered a new spring. Bear Woods shipped the order quickly. I believe the spring was the cause of the problem, but while installing it I lost my grip on the spring (it is small) and it went flying off somewhere in my workshop. If you decide to make this repair be VERY careful handling the spring. It is tricky to install, and it's the kind of operation that requires three hands to complete. I never did find the spring. I ended up ordering a whole new upper assembly, and it works perfectly,