Welcome to the forum! Your Amazon has great longevity, so you are doing many things correctly! As Allee suggested, having a vet consultation may prove very helpful. Perhaps this is nothing more than aging, and positioning perches, toys, and feeding/water dishes to a more comfortable position will make a difference. Reorganizing so the occupied space in the cage is less "vertical" will lessen the severity of fall and potential for injury.
Good luck to you both, and hopefully more members with similar situations will contribute ideas.