I backed mine up a few feet at a gas station once. At first glance it appeared to cause no damage at all. When I got to my destination and disconnected it took all my strength to slide the tow bar arms back in. I still use that tow bar but it is very difficult to push them back every time I disconnect. Evidently it caused a slight bend in the arm, invisible to the eye, but there non the less. Mu suggestion...NEVER back up.
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