I noticed an RZ Pro II body on KEH 'as-is' for $29 and my gambling nature couldn't resist! Turns out the issue was that the gear that couples the fine and coarse focusing knobs has lost some teeth which made both knobs pretty gritty. I removed the coupling gear, disabling the fine focus and giving me an RZ I + half shutter speeds.
My question is, does anyone know of a shop that carries little RZ parts like this? I tried JD Cam Tech in UK but they aren't interested in selling the parts - they want me to ship it there for them to repair which will cost far more than it's worth.