Recently I have been unable to get the front bonnet to lock when closed. There is a 'click' on the locking mechanism on either side of the bonnet when I make a firm effort to close it, but a fraction of a second later the lock 'springs' and releases again. I have looked at the mechansim and note that the locking hook is raised correctly, but the piece of metal which should descend to hold the lock in place seems to be jammed or immovable -on both sides. Is my description accurate enought to explain the problem ? Perhaps someone else has experienced this too.