I've abandoned the Yaesu rotor az-el system for AlfaSpid, after 15 years of breaking az-el rotors. For the time I had a satellite or few that I had to actively command, I always kept a spare rotor system to swap out quickly. As a result of that, I have accumulated a large pile of rotors, each with some issue I never got around to fixing. I currently have three 5500 series, and one 5400, each with some unidentified or forgotten fault. I know on one I swapped out the motor in the azimuth rotor from a donor G450, and ran it for several more years until the elevation rotor froze.
I'd really like to deliver this whole batch to someone at Dayton. A handy person with time could probably make at least three work again, and probably all four. You might get 1-2 from just swapping halves and control boxes around.
Email me with an offer if interested. I'd prefer not to ship. I can take some photos this weekend. I might be interested in trades or partial trades as well.
73, Drew KO4MA