Very very gradually change seed for pellets in his food bowl. Do this over the period of a few weeks/months, not all at once. Parrots are very capable of starving themselves to death if faced with a totally new food and nothing that is familiar.
You may want to try different brands of pellets, Parrots will sometimes reject most brands and then all of a sudden like a different one. Some parrot food companies offer trial size packs of pellets, so you dont waste a lot of $$. Aim for pellets that have the least amount of sugars, fillers and such, and no additional vitamin fortification. A balanced parrot diet of veggies/pellets/ and small amount of seed and nuts will provide all the nutrients he needs, no need to add more vitamins! But in a practical sense, the best pellet is the one that your parrot will eat - serving the best one is useless if he wont eat it it!
