This post is for the benefit of future readers who are struggling with the front latch not working properly.
Mine wasn't engaging properly and before I started fiddling with it, I decided to remove the entire top/seat plate holding the "U" latching catch. After all, our Burgman AN400 only had a rear locking mechanism.
After removal of the plate, it made no difference to the operation of the seat's closing and locking capabilities so I just bagged, labelled and stored it away in my SWing parts box. It's 100% intact so totally re-attachable if needed and I have a a backup plate should the rear one pooch for some reason.