Often a short section of rib can be resoldered without completely relaying the rib and reblacking.....if the rib can be pried up a bit and the mating surfaces can be scraped clean, English solder can be used to resolder the area...Brownells sells this - made by Swif...it is a paste and is applied to the mating surfaces.... they are then tied tightly with wire....the excess solder is wiped off and the area heated until the solder flows....clean up of the newly soldered joint can be done with a wire wheel, without damage to the bluing....if a bit of touch up is necessary to the joint, OxphoBlue paste can be applied while the joint is still hot from the soldering and wire wheel cleaning.....I should warn you that if an attempt to hold the rib down with epoxy has been made, this job will be extremely difficult without removing the rib - DON'T DO IT!