Hi, couldn't log in today for some reason. If you have the dizzy mounted on the back of the head, its easy to pull and replace. Pull the spark wires(remember the order), remove the cap and rotor, undo the two 10mm bolts on either side and pull the unit off the back. There is one large o ring, one small o ring on the shaft and there is a seal in the bearing unit. I tried to punch out the pin and replace the bearings and seal without success. I'm told it is tough. I ended up buying a rebuilt Bosch unit for $199. A Lot of money! My problem was an oil leak tho, I didn't have any noise. When you replace it, push on part way and rotate pushing gently until the dogs drop in, they will only go one way as they are off set on the shaft. Replace the two bolts to seat it tight, there is no timing adjustment to worry about, the crank sensor does that.

Ed