Not sure if this is the right term, but basically I've got a Saracen Backtrax (mid - late 90's?). When I was cleaning it down one of the plastic collars that sits behind the canti body snapped in half. One of them has an adjusting screw mounted on it, one hasn't. It's the one that hasn't that's snapped. Do I need to replace this or will the brakes work ok without it? The spring is exposed now? At the moment half of the collar is still in place. Any advice gratefully accepted.