Back in the early '80's, I was a terminal agent for a Canadian charter airline. At that time, we operated three B 707's. Air Canada handled us, and sometimes their operations were more important to them than their contract with us - things were occasionally got wrong. One of these was using the wrong towbar for pushback one cold winter morning. There were two possible towbars, both fit, but only one was right. The wrong one was apparently for a B727, and although it fit, required a pin be pushed through the link of the towbar and link on the oleo. The proper towbar had a mechanism inside like a door lock, instead of the pin.
The towbar was installed, fueled, and the passengers, and baggage loaded. No one noticed that the towbar and pin had now passed down between the two nosewheels, as the oleo compressed. It was first noticed with four engines running, pushed back onto the apron - couldn't pull the pin, it was between the nosewheels. All kinds of worried looks, and fuel being burned, while still tying up a gate. I suggested to the director of operations that we ask most of the passengers, to get up, and slowly walk to the back of the cabin until the oleo rose enough to pull the pin. He thought about it, but did not want the embarrassment, and having to reseat everyone again. Instead, a hacksaw was found, and the pin cut, and slid, and cut and slid, until it was out. I recall it taking 15 minutes or so. After that, one of my jobs was to assure that the correct towbar was connected.
Experience is valuable!