The ends of center channel 6T6-3 require joggles to fit inside elevator ribs so I created a jig from a piece of hardwood that conformed to inside profile of channel then sanded and filed recesses on each that were used to swage the channel using vice and mallets.
There is nothing specific on the drawings or in the assembly guide relative to mating the truncated elevator rib to the channel. Figured the best solution would be to joggle the flanges to fit inside the channel. Modified the rib form block by filling depressions that could were used to swage down both flanges.