[Arran]

If the dial cord is original, or an older replacement, the cord is probably stretched, even if it is routed correctly. If the cord is not rotten, which many are and will snap if you pull on them too hard, then you can add an extra turn, or half turn around the shaft the tuning knob goes on. Most people seem to be terrorized by the prospect of stringing dial cords, which is where these short cuts like rosin come from, I am not, so my inclination is to just replace it along with the paper caps. Fly line backing, used in fly fishing, is a reasonable substitute for dial cord, it's sold in sporting goods stores, the ones that sell fishing rods, and lures, and even Walmart. Fly line backing is rated for tension in pounds, 30-40 pound test is more then strong enough.
The original knobs did not use sets screws, they were push on knobs with a steel spring, the repro ones may or may not have set screws, which many annoyingly do as if they are accurately molded from an original knob there is a slot in the back to accommodate the spring. My 42-327 has similar knobs but they are Bakelite rather then Tenite, the latter is what the 42-380 used in the knobs, which is why many or distorted, or crumbling today.
Regards
Arran.