Carb gasket ford type carbie

[MH55k]

Has anyone replaced the gasket in there e27n ford type carbie (lump of iron on the side type manifold ) as mine blew out a swction of gasket today while I was marking out for our plough day on Saturday . Now I have to replace itin the feild and was just wondering what the procedure is as I've never done one on a hi major any help would be apreciated thanks