Thank you - this is helpful. As long as you're seeing droppings with any solids whatsoever in them, he's eating, just not letting you know
Now, what has me more concerned is the yellowish part of the urates. No matter what the seed makers say - there is no such thing as a 'healthy diet of seeds' for in-home birds and we see a huge number of them, as they get older, develop hepatic lipidosis because of the high fat diet without a day full of flight to burn it off.
It's like feeding a human toddler nothing but ice cream and candy while they live in their bedroom for years. Everything seems just fine until that first heart attack or diabetes or a host of other health issues.
The addition of new birds may have been a stressor - and that stressor could have lowered his "masking" ability just enough to have him showing symptoms. Birds, over 65 million years old, are among the most expert "maskers" in the animal kingdom, which helps explain part of the reason they survived the last mass extinction.
I would have to recommend a hands on vet visit to at least check a fresh dropping under the microscope for yeast/fungal infection and a blood chem to test liver values at the very least. As you know with your admirable history with psittacines, it only involves a nail clipping a bit short enough to get a drop of blood. It's no more painful than us having our finger pricked to do the same.
Then let me know what the vet finds and we'll work together at addressing whatever it is going forward.
I work with a fellow who has international bird shows - I met a 90 year old 'too who was amazing at holding actual conversations! 90 years old! I've only met a few humans at that age who are able to hold conversations!
Let's get yours there too
I can also help you convert to pellets - no matter how old the bird is. I own BrokenBirds.org - all macaws (though currently we do have a 'too) who have been horrifically abused and, well, broken in some way (blind, crippled, etc) and when the come into the sanctuary, some have been seed junkies for decades. I get them all converted, usually within days. So I'm positive we can do this
Sound like a plan?