I recall adjusting the fixed part of front catch by loosening its fixings to inner wheel arch slightly and tapping it down to give snugger fit before re-tightening fully. The mounting holes are either slotted or oversize. If you can feel movement of bonnet at any of the four catches when secured one or other needs adjusting.
As alluded above the sliding bonnet part should be under spring tension and not at the limit of the slide travel when fully secured. Note full movement with bonnet released first to make this check.
