Modern Vespa

IIRC my seat latch has always been a bit spotty, but it did latch most of the time. Lately, it doesn't. It simply won't latch when the seat is down. I've fiddled with the mechanism from the outside, everything moves, but the little piece that holds the seat won't stay locked. The electric release sounds, but seems besides the point as it's already open.

Has anyone had a similar problem? The easy solution is to just ignore it...(I'm not that concerned about people looking under the seat and usually valuables are in the topcase), but I like the idea of things working the way they should.

Anyone been down this route? It looks like access will be by removing the central plastic panel just behind the seat?

I worked on the latch mechanism on my Liberty 150. I have no idea if your BV and my Liberty are similar enough for me to make comparisons. But in the mode of being helpful, here is my reply explaining what I did from my post on my latch problem (The original post is here https://modernvespa.com/forum/topic195598#2767214):

Dear Old Schooot,

I closed up the top of the scooter, thus hiding the top view just before I read your post. Here is a side view.

I'll start with the most obvious, at least to me. The red and yellow blocks are the terminations of the manual latch release cable and the button-activated latch release (I don't know color goes with which activator).
To the right of them coming out of a hole in each color block you can see the actual cables.
To the right of the actual cable are the two over-molded stiffeners that help the cables make the turn coming from front of the scooter down the right side and making a turn into the center of the scooter to where the latch is.
These over-moldings have grooves towards the red and yellow cable terminations. The grooves fit into retaining notches built into the latch mechanism. I can see them in the photo, but I'm not sure how to locate them for someone else. The latch bracket makes a "3" shape with the top arm of the 3 above the red cable, the middle arm between the two cables and the bottom arm of the 3 below the yellow cable.
In the foreground, and unimportant, is an electrical cable coming from the right of the photo and a screwdriver coming from the left of the photo holding said cable out of the way for me to take the photo.

It is nice to get a reply and request from the most prolific Liberty poster.
It is foggy here as I type this, and so I'm remembering your lovely moody foggy photos of your Liberty.

Thanks,
Marc
Seat Latch Cables seen from right rear.

The mechanism is pretty similar. Was a PITA to get to where I could access the latch adequately, but I didn't waste a lot of time on blind alleys. Figured out what's wrong.....one of the cables retaining too much tension, but not why. It would be nice to have the front end exposed to see what the manual latch is doing, but I'm not going there. From this point on, the manual latch is the nuclear option for the seat...I've only pulled it to see how it works...likely the start of my misfortune.