Mark V Manette Disassembly Difficulty

Working on the wiring for signals and horn on a friend’s Mark V has led to needing to take out the steering manette (which I understand means remote or controller in French). The manette assembly with wires and horn push button all came out of the steering column just fine.

Trying to open up the manette to repair the “open” wire condition on the right turn signal and horn (USA car).has led to a roadblock. Your techniques would be most appreciated.

The three small screws to remove the bakelite assembly from the tube carrier had one screw come out fine and two are frozen. I have spare screws from another manette. How do I free these two frozen screws? The hole through which the screws are accessed prevent a drill and extractor getting a straight shot. I’ve got Kroil soaking a couple days now without success. Made a long screw driver with maximum blade size for screw rotation and straight action while pushing downwards. Would freezing the screw heads be advised? Other techniques? These two stuck screws are into the brass inserts in the bakelite.

Or manette is Italian for handcuffs. According to the internet…
Can you get a soldering iron in there and heat them up a bit? Heat worked very nicely for me with some broken off grease nipples in Mark V saloon door hinges.

You would have to be really careful applying heat, as it would transfer into the bakelite and potentially cause burning in the bakelite. I found out the hard way working on a regulator…

It’s the same manette as a MK VII and XK 120.