They attach with shackles to the jib block support wire and are not held up with springs. There should be enough tension on the wire to keep them standing up on the tramp.
You can use the old style Hobie 16 jib blocks, just cut off the traveler slider. Be careful not to cut the pin that holds the block to the car. Also, when installing the blocks on the 14, use a shackle with a pin and ring-ding. It is difficult to get the shackle on, but it won't work its way loose as a regular bell shackle would.