Can you post a pic of Chip? How old is he and what do you feed him? Any other unusual behaviors you've noticed?
From what you described, it's possible there may be more going on than just molting. Since he'll need adequate protein to help him regrow his feathers, you may want to supplement with some of the ideas in this
thread.
Have you tried
fermenting his feed? I ferment a formulated feed for my chickens, ducks, and geese, and they all love it. Waterfowl like wet food, so it's generally a very easy transition, and it has a number of
benefits.
If you haven't already, I'd try to offer a supplement like poultry Nutri-Drench to address possible nutritional deficiencies (and it should help perk him up). Hope Chip's feeling better soon!