I've never worked on this vintage Nikkor, but most lenses of this era are built the same way. The trim ring will have to be removed first. Since there are no spanner slots, you'll have to use a sink-stopper of the right diameter to unscrew the ring. Once the trim ring is off, you'll probably see another ring with a pair of spanner slots. Unscrew this ring using a lens spanner and you should have access to the front element (just turn the lens over and it should drop out). Cleaning should be an easy. Don't worry about aligning the element, it will drop into its own little "well" so there's no chance of putting it in the wrong way. Follow the reverse procedure to reassemble the lens, and you should be good to go.
Originally Posted by kitanikon