Its been awhile but I'll try to answer your question as best I can. Btw Gr8day is correct you probably will need to grind the peened area of the yoke screw so that it can be removed. however if I remember correctly you will also have to remove the whole top lever assembly. to do that you will have to loosen the set screw on the retaining nut and remove the retaining nut (that requires a spanner tool which you will see). You also need to remove the combination top lever spring/safety rod screw. This spring is like a mine field for the uninitiated, note that there is a small ball shaped end on the screw that fits into a cup shaped end of a pin for better words. Here's where things get interesting, behind this pin is a strong coil spring. It is VERY helpful to remove the pressure on this spring (a third hand is helpful here). If you do not remove the pressure on this spring in all probability the pin and spring will shoot across your shop floor and you will spend the next 2 hours or days looking for them. BTW, if there is a way to remove the yoke without doing all of the above I would like to know it and I'm being sincere about this.
Doug
