One of the float bearings on my 1938 JD A carburetor was very stuck. After a month of soaking, and multiple attempts to loosen it with heat, I had to resort to drilling it out.
The float bearing is brass, so I drilled out 90% of the diameter, and then finished it up with a left handed drill bit. It broke loose and backed right out.
This is always a good sight to see after an hour of work: