Joe Poyer's book, "The American Krag Rifle and Carbine", has dimensions and descriptions of the changes to carrier-arm/follower (assembly) parts.

I would personally focus on what is causing the assembly to 'drag' or limit its travel, at the end.

Pay especial attention to the 'pivot pin' that the follower hinges on in the carrier-arm. The ends of this pin should be flush and smooth.