I need to replace the float valve assembly in a JD 300 carburetor. The float valve is easily removed but I can't figure out how to get the valve seat out (brass part, center of photo). It's a 3/8" threaded fitting but there's no room to even get a thin-wall socket around it. I've tried putting a drill bit inside and backing it out, no dice. Is there a special tool need to get the valve seat out? My alternative seems to be to file down a bit of the carb body which forms the support for the float hinge pin just enough to get the thin-wall socket in. Other ideas?
John Deere 300
16 hp Kohler K-341AQS engine, spec 71169A
Carburetor JD # AM35801 (Kohler # 4505308, pre-55000)