abe's explanation of using hog rings to join adjacent springs sounds like a good solution to the sagging problem. In my case, however, the 2 broken 'springs' were those L-shaped wires running across the base (see engatworks's picture, which shows the spiral springs in the corners, as well as the wires). And, the breaks were at the corners of the wires as well. Split tubing was the only way I could see to rejoin these, although I suppose a piece of wire and several hog rings could be used as a 'splint' of sorts, but this wouldn't be quite as tight as a crimped sleeve..
