2N Carb Question - Rebuild?

I'm in the process of tighening up the 2N that I bought last month ... mostly small parts replacement for now, just to make it start and run regularly. While taking off the aircleaner to get to the back of the dash for a couple of new items, I noticed that the top hose was disconnected and the whole thing was pretty filthy. I'm going down tomorrow to a friends garage to use their parts washer to wash out the mesh in the body and reinstall with new hoses.

New plugs, battery and cables have made it start much easier. Still waiting on those wiring harnesses for Christmas from Mama.

Tonight, I went down to start it, just to see how it did on a colder night. It started right up and idled without any added choke. But then something odd ... as it warmed up it started trying to stall unless I added choke. My thought would be that it would want a leaner mixture as it got warm, rather than a richer one.

The tractor came from an area at 4800 ft, Tucson is 2300. I'd tried adjusting the idle mixture screw a couple of days ago to get the idle better ... but it's almost all the way in. Haven't worked on the speed screw yet.

Another factor is that there is blowby from the oil breather.

Does it sound like an adjustment problem or does the carb need a rebuild?

Thanks,

Rod