Came upon this video on Youtube about a bent clutch plate drive pin. The persont hat uploaded the video stated that it caused his propeller assembly to wobble. Makes sense, as the clutch plate sits on the drive in and it's the drive pin that spins the clutch plate. I would think the milled channel in the clutch plate would need a very tight fitting to prevent any play between the pin and the clutch plate.
Might be worth a try, since you've already replaced everything, apart from that pin. The following is a video of my own SS Viper DPV. Mine has brand new bearings and a new shaft seal. Everything plastic, apart from the blades has been replaced. I did replace the clutch plate drive pin, although I have the original clutch plate. I don't see any wobble and I cannot detect any play when I grab the hub assembly and try to move it sideways.
O.