And done: I found that a pipe was popped out, a leg. Under tension. I spent some time thinking how to fix it without injuries. Used a lashing-strap. Wrapped a couple of times around the top of the leg and then pulled on the ends from a safe distance and with the foot as a lever. Easy! Used the same lashing strap to put the last spring in. Could not find the dedicated tool. I usually use a spring to tension and slip in the rest of the springs.