My Morgan it‘s nearly the same. I ask a dealer about to cure it, the answer was: it‘s difficult.

Here is a posting from a swedish member who converted his Mog from the full screen to Brooklands. He found a lot of silicone under the seal.

My idea is (the Mog is not so old) if I‘m more fearless undo the screws, lift the screen a little bit and fill the gap with something like this:
https://kunden.stahlgruber.de/Kataloge/lackiertechnik/index.php?sb=223601

Greets René

2018 plus4 (sports green)
with a homemade really shiny red tinted dash…