The most common version is quiet: the door starts making a grinding or popping noise as it travels, usually near the top or bottom of its run, before it ever actually jumps the track. Some owners notice the door closing crooked, one side reaching the floor before the other, which usually means a roller or hinge has already started to walk. Others get a sudden version - the door comes off track all at once, usually when it's been forced against resistance, or after a car backed into it or a panel got bumped. If your door reverses on its own partway through closing, that can be the opener sensing the extra drag from a misaligned track rather than an obstruction. Across the owner-occupied houses in this service area, this is one of the more common calls we get on homes with original or early-replacement track hardware, simply because of how much of the stock dates to that 1970s-through-2000s build window.