My little rochester was pretty beat up as well, but after a $15 carb kit and a days work cleaning, it ran like a champ (for a carb) I'd try rebuilding it myself first. If by the po using a hammer to tune it, you mean the chunk that looks to be broken off, someone has already rebuilt it once. You have to break off a plug to get to the mixture screw which was sealed at the factory.
'81 CJ5, efi 302, AX-15 5 spd, On Board Air, wrangler spring conversion, Astro van Hydro Brakes.
Soon: Custom cut Dana 44 front, wide trac solid axle amc 20 rear, SOA,