Oh no I got him a blue one lol he doesn't seem to have a color preference with his toys or anything so I hope he'll be ok. He loves to watch out the window so I'd love to be able to bring him for walks when the weather cooperates, there's a nice park a couple blocks from me that I'd bring him to.
Please tell me how you trained him, and how long did it take?
He's so adorable sitting in that tree
I don't know exactly how long it took because of the blue harness fiasco, but I would say a few months.

I started by letting him get used to the harness, getting him to touch it with his beak, step over it, etc. Everytime he did a good action I rewarded him with a safflower seed or other treat. I then made a huge loop, big enough for him to run under, and placed a seed on the other side- so he had to run under the loop to get the seed. This helped create a foundation for the head loop training. After he was used to being around the harness and such, I began to teach him to put his head through the loop. I started by using the leash part to make a loop (the green part of the leash though) so that if he freaked out I could just let go of the loop. To train him to put his head through; I either held a seed or put one on the other side of the loop, so the only way to get the seed was to put his head through the loop. Once he was comfortable with doing that, I gradually reduced the loop size, until it was the size of the actual head loop. I then taught him to keep his head in the loop for a bit by continuing to give him seeds while he had his head in the loop.
Grumbles is very tame and is completely okay with me touching/moving his wings and such, and I can easily hold him in my hand without a complaint. But after I trained the head loop, I taught him to be okay with the harness touching him and rubbing against him. Especially so on his back, stomach, and wings. Then one day I took a chance, and let him put his head through the loop, then, while leaving it loose, putting the harness under the wings as it would be put on. I just didn't tighten it. I gave him a treat then after a few seconds carefully took it off. To this day he is okay with putting it on until I have to tighten it, then he tries to bite. But when it is on and we are outside that is forgotten haha. It almost helps if you have another person to help tighten while you hold it in place, or train your bird to be okay with putting it on while on a perch. Grumbles likes to be held in my hand to put it on so it is hard sometimes, but manageable.
The main thing is positive reinforcement, basically reward any and all good behaviors and ignore the bad. Also, don't end on a bad note- always end on a good happy note. This will help with future training sessions.
I think I covered everything, if I missed something or you have any questions let me know!
