I had the same issue one time after replacing with a new clutch. Later when removing the clutch again, I found the clutch disc was not uniform in thickness. I could see it with the naked eye. After replacing that disc, the clutch is now smooth.
I can remember back in the day, I used a rat tail file and inserted it through the bushing. Then with the tire and wheel on their side rolled the bushing with the file inserted until the bushing fit the king pin.
I have a ford 8N tractor. Is this engine basicaly the same as the model? I know there are diffences but it looks a lot like the model A. It does have inserts that the A does not.
When I rebuilt the steering box on my 8N tractor, I used John Deere corn oil. It comes in a tube just like grease but is not a thick. Works freat on steering boxes and does not leak out. Just insert a tube in yoiur grease gun and put it in the steering box. Any John Deere dealer should have it.