Well picked up another Model 5 series 1 today, put some fuel in it and give it a couple of pulls and it fired, the needle was not shutting off the fuel and neather was the tap, so give the carb a quick clean out and it runs really well. It does have a strange bottom case letter "S" rather than a number so ?? here are a couple of pics.
I give it a hit with the hose and it come up with a fair amount of good original paint left on it.