OK, here's what I've been giving Bubba. This is not my creation, it's from nnbreeder with a couple small variations. The original is on page 2 of this thread, I think.
1 egg yolk
1 tsp honey
2 Tbsp plain yogurt
3 Tbsp unsweetened applesauce
1 tsp pediatric electrolyte
Blend all that stuff together
Cut a daily multivitamin tablet into quarters
Grind up some feed to a powder, along with 1/4 of the vitamin. (I'm using lay crumble, but I'm sure pellets or mash would also work) Then mix the powdered feed with the wet mixture, adding enough to get a paste about the consistency of thick cookie dough. You may need a half cup or more of powder.
Then I form it into little chunks of an appropriate size for the bird. You'll have enough for a couple of days, maybe three.
Bubba loves it and is doing much better. He's now eating the mixture on his own, as long as I hold it in the palm of my hand for him. Tonight, he pigged out till his crop was stuffed, but he doesn't seem to be eating crumbles out of the feeder. Maybe he's getting spoiled.
I also have not seen him drink, so I take a syringe and put just a few drops of water in the side of his beak. He swallows some of it and some of it just runs out. If he wants to swallow it he tilts his head back and down it goes. I don't think there's much risk of it going down the wrong pipe the way I'm doing it.