You could also pull all the carb and reed mounting parts and straight edge (metal architects scale) all the flange surfaces. Do the same on the engine. Look for any cracks or deformities around all the screw bosses. This has been an issue with 3w plastic reed blocks where screws have been tightened without uniformity. The plastic reed blocks also manage to continue compressing at the screw bosses over time, typically with one or more ending up set tighter than another, creating later leaks.