We're a bunch of volunteers and starting a new scheme in our community. Your website provided us with helpful info to work on. You have performed a formidable task and our whole group will probably be grateful to you.
Most locks have seen on bikes are held in by tangs at the rear of the mounting. I have only seen one with a nut. You need to work out how to remove the panel it mounts on. I gather you are replacing all locks with new.