I have a NordickTrack Z 1300i treadmill, which I purchased in January 2019 and have used since then. In October 2021, while I was running, the retaining bolt that connects the left side of the belt roller to the frame sheared off, causing the belt to lose tension on one side and creating a very dangerous condition as the belt suddenly dropped and became slack on one side while running at high speed. I contacted NordicTrack and they sent a replacement for the bolt (actually, a bag of 10 bolts). A week ago, however, on November 12, the same bolt – the one I had replaced the prior year – sheared off again in the same way. I was running at 12 mph (5:00/mi pace) at the time. I managed to catch myself and was not injured, but again the condition was extremely dangerous.
The photos included show the treadmill, the product information sticker, the location of the bolt, and the sheared-off bolt after I removed it and replaced it.