Thanks - I showed the video to a vet and he suggest he had something stuck in his caw so same deal, just less sexual

Under the circumstances I don't think it was a mating thing (long zoom lens, I wasn't nearly as close as I looked)
Both birds have been out of the cage most of the day. Curly went in of his own accord - I tried targeting him there but he's not that stupid

I got him close but as soon as the target was far enough into the cage that he couldn't just lean, he stopped playing. But it wasn't long before he went in himself and he didn't make a fuss when I closed it up, unfortunately my soothing 'good boy's and treats were disturbed by a squirrel throwing himself at the window, startling Smeg, sending him screeching across the room which mean Curly flew off to the other side of his cage. I put some peanuts in his dish and later we did some easy targets. He's very sensitive though - I think he doesn't like my shirt, or maybe its long sleeves. Yesterday I was petting him inside his cage, this morning he runs away if I go near the cage (before I let him out). He still bangs on the bars and bobs up and down wanting me to come over but when I do he backs off or flys to the back of the cage.
Thanks for the apple tip, its mostly working a treat with Smeg (Curly had one small bite then took the whole piece on the next turn). He's occasionally snatching but it seems the closer I hold the treat the less he snatches. Sometimes when I offer the treat he'll puff up and open his beak but not go for the treat, usually that's followed by me getting bit but if I move the apple piece closer he'll take a gentle nibble. He sat on my shoulder earlier in the day but Curly flew over and scared him off. Later in the day he came and sat on the sofa with me and ate my notes - I offered him nuts and he threw them on the floor, he attacked the apple and was uninterested in the toilet roll tube or cuttlefish, my work notes were what he wanted

I've found he has a thing for chicken wings. When I had my dinner he came over and actually sat on my knee. I offered him a bone but he just put his head down for scratches. When he'd had enough of that he chewed a little bit of chicken bone then tried to go to sleep on my foot (but my foot was going to sleep so I had to move him)
This evening I've had him touching the target with my arm just below my feet. It seemed to be going well but he attacked my arm... and the not flinching thing is still a work in progress.
Seems to be the same story with both of them, no problems trusting if you've got something they really want

I know every flinch is a setback but its so hard.