[DanEC]

Where those diaphragm housings bolt to the carburetor body there is a small cork o-ring gasket that seals the vacuum passage from the carb. It's something than can go bad or may have got lost or misplaced when someone had them apart. That would prevent building vacuum although if you can't get either carb diaphragm to hold vacuum with a pump - it would be a bit unusual to be missing the gasket on both of them. If this is your issue you aren't getting secondary throttle either.