In this case, it may be necessary to incorporate a locking mechanism such as slots 18 and rivets 20 of FIGS. 1A???1D or any other locking mechanisms disclosed herein after and illustrated in FIGS. 3A???B, 4A???F, 5, and 6A???E into the device to restrain further radial expansion of the spring 12 once the desired track opening is reached.