Hello Ollie and Lemmy! Ah yes - the perennial issue of getting our little plets to eat food that is better for them when they’re loving their seed diet. They sure know how to show disdain for these healthy alternatives.
I personally wouldn’t recommend taking the seeds away entirely and only leaving the food he has clearly disregarded. But you can take the seeds out of the cage for an hour and if he will try the pellets and other food. The problem with that is that they do figure out that they just need to wait and those delicious seeds will come back. When I used this approach, I would only put pellets in her cage. I had other ways of encouraging her to eat veg and I wanted her to have only one option. It worked to get her to at least try the pellets (which she loved once she gave it a try).
I also had much more success with Kiwi introducing one new food at a time. It was like too much change would just shut her down. Kiwi was always a good eater, but she never liked chop/mash. She likes her veggies one at a time AND served to her taste. So Broccoli raw, carrots cooked and mashed, corn off the cob (which is too bad because I have heard of some fun times for parrotlets with corn still on the cob - Kiwi was terrified of it LOL). Strawberries quartered - the whole ones freak her out. Forget blackberries - they’re evil (as are raw carrots). Lettuce must always be hand fed. You get the idea. Just experiment with different ways of introducing it. Someone once suggested chunks of veggies on a skewer hanging in the cage so they had to work for it. Kiwi didn’t take to that at all but it was such a great idea! Oh - and Kiwi loves it when I cut off those little broccoli granuals and put them in a dish. She will eat a sprig of broccoli but she loves it when I do the work for her.
Kiwi gets whatever we are eating and as eating is a social activity for a bird, it might have helped. I see you tried that too but he might have noticed you faking it. I wouldn’t put it past these clever little guys. Try actually eating something and passing him a piece as well.
At the end of the day, I think it is persistence, patience and creativity. Bear in mind they have very few taste buds so food is probably not that tasty to them. This is why they probably like hot peppers - my avian vet explained that they don’t have the mucus membranes we have so they don’t feel the spicy burn of a hot pepper, but they probably get some flavour. Kiwi loves those hot peppers with their seeds - she mostly eats the seeds, but she gets some of the pepper itself digging the seed out.
Keep us posted on your progress! It’s so rewarding when they finally start trying something new!