I think the answer is to use a bit of "brute force and ignorance". The brass cable connection is only pressed in to the brake plate, but the problem is that it's not easy to grab hold of the connector without riking damage. I've done this job on my 50 Sport and 90 Deluxe, and I used the threaded collar from and old speedo cable - thread the collar on and you should be able to grab hold of it in a vice. (Don't wind the vice too tight, though, or you might crush the brass fitting).
You could also try levering from inside with a small screwdriver blade between the inside face of the brass connector and the speedo pinion.
The connector is probably only tight from corrosion, but it should come out with a little perseverance.
Good luck,
Graham
