ORIGINAL: r/cheliman
Is the main shft a ***** to fix I can see a slight wable in the gear and thought it might be a bend in the main shaft. I have a new shaft but didn't really want to fix something that is not boken. If it isn't that hard I will swap the shafts and see if that is it.
I just replaced mine for the first time last night and really did not think it was hard at all. My main gear was tracking straight but I had a wobble in the head. I was intimidated at first but it went rather smoothly.
I just disconnected the servo to swash linkages. Unscrewed the head from the main shaft and removed it with the swash still attached. I then loosed the main motor and slid it back Next, loosen the lower lock ring and an unbolt the main rotor gear. Finally remove the main rotor gear and slide out the main shaft. Then reinstall everying in the opposite order. All in all I think it took about 30min.
Mine now spools up and runs silky smooth with zero wobble. Good luck!