A word about this slotted nut you are after. Once the top clamp is off and the slotted nut is off the triple and the lower part of the clamp will drop. It might be held up a bit by cables or something so don't damage stuff and clean then grease the lower bearing too. You'll want to use brake cleaner or carb cleaner to get the old grease out but make sure it is dry before adding new grease. The top bearing is much easier to clean and grease, you will have it in your hand.
When placing the slotted nut over the shiny washer that protects the bearing notice that the slotted nut is chamfered. (I think I spelled that right. It's a word not in spell checker) The slotted nut is smaller on one side than the other. Notice that one end is flat and the other end has tapered edges. The side with tapered edges has a smaller contact area. The side with the smaller contact area goes down against the bearing and the side with the full contact area goes up against the top clamp.