I'm sorry that your question wasn't answered in a timely manner. We don't have many avian vets on this site.
Yes, because nutritional imbalances are a common cause of illness in our pet birds and are likely to underlie his delayed molt, seeds should compose less than 20% of hisdiet. A diet of mainly seed and nuts has excessive fat, carbohydrates, and phosphorus; marginal protein; adequate vitamin E, and are deficient in amino acids, calcium, available phosphorus, sodium, manganese, zinc, iron, vitamins A, D3 (necessary for efficient absorption of calcium), K, and B12, riboflavin, pantothenic acid, choline, and available niacin. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat.
You're going to have a difficult time transitioning him to a proper diet and so please take a look at how that might be done: http://www.harrisonsbirdfoods.com/using-our-foods/small-bird-conversion/ (Disclaimer: I have no vested interest in Harrison's.)
A delayed molt can also be addressed by establishing normal diurnal rhythms by ensuring birds get at least 12-14 hours of "sleep time" in a darkened, quiet environment. Simply covering a cage in a busy family area is insufficient. Nutritional problems must also be corrected. Please respond with further questions or concerns if you wish.