It looks like there's a pair of holes in the metal plate that might fit around the rubber lugs in the jet fins -- if that's the case, all you need to do is buy a couple bolts, fit the metal plate around the rubber lugs with those holes lined up with the hole through the lug, and bolt them in place.
Alternatively, you might be able to use the existing bolt portion to attach the spring directly to the jet fin lugs where the pins normally go, but you'd have to make a small slot in the center of the rubber lug for the spring end to slide into, and you'd probably need to discard the existing metal plate and plastic (rubber?) spacers.