Roof rail gutter finish?

Been down this road and it's a real pain to replace. Two part glaze putty would probably work fine for touch up. If you decide to replace it look into getting some self leveling seam sealer from the auto paint supplier. SEM, 3M, Lord Fusor all make them. I got the best results with Fusor #129.

Pick the wrong stuff and it'll end up in a puddle next to your car. Scroll about half way down this page for my experience: http://70duster440.com/bodypaint.html

If you haven't removed it yet, I suggest just touching up the cracks or other defects with the modern stuff or body glaze.