Heat the Alloy carb body under the screws, use a heat gun, don't get it any hotter than your finger can stand. You want to make the alloy body expand and hopefully loosen the chemical bond in the screw holes from two metals that form a undesirable chemical reaction from touching each other. After you get it hot, immediately spray your favorite brand of Nutbuster, Liq Wrench, I use Aero Kroil, It's all good. You now have your best shot at getting the screw out if you've cut a decent slot and have a screwdriver that fits tight. I lose patience when I'm trying to accomplish things and just tack a nut with the I.D. of the screwhead on the offending b!tch with my tig torch and wind it out. Never fails.
