Just a little observation I made today. If a bird isn't eating its fruit and veges, it may just be the way you are presenting them.
Last Tuesday I got a pied mutation Rainbow Lorikeet. I know I've only had him for less than a week, but currently I've been putting his fruit and veges in a container and I haven't noticed him really touching it. (For those interested, the fruit and veges are apple, kiwi, nectarine, pear, bok choy, broccoli, and carrot). He doesn't even really touch the apple.
Now I know he certainly likes apple, so instead I cut a piece and wedged it between the cage bars and he goes crazy for it! So he is far more likely to eat apple wedged between the bars than in a container. I tried this with the other fruit, he showed interest but hasn't really gone for them yet.
Today, instead of putting the rest of his fruit and veges in a container, I put them in a foraging toy. Specifically a Jungle Talk Snac 'N Play:
Jungle Talk - Treat Dispensers
I put it in the exact same spot as the container, and he dove for it! This may partly be because I had trouble clipping it onto the cage so it may have looked like I was 'playing' with the foraging toy and he wanted to join in the fun. :P Well he's been busy pulling the food out, nibbling it and dropping it (he hasn't learnt to hold things with his feet yet, and some of the veges he may just be playing with but at least he's getting a taste of them). Plus he plays with the rope on the bottom of the toy while he's eating.
So it may be all in the way you present the food. If putting it in the container doesn't work, try changing the container's location. Try wedging food between the cage bars or putting it in a foraging toy. Texture of the food is just as (maybe even more so) important as taste. So try cutting the food in different ways (grating, etc) and different sizes to attract your birds interest.
Showing interest in the food yourself (pretending to eat it) can certainly help.
I know this is probably common knowledge but just an example of what happened today which drastically changed my bird's opinion of his fruit and veges. :)