Linked below is a relatively short video describing the replacement of the tachometer drive oil seal on the Honda CB750K. When I got this project last fall the bike was leaking oil from almost every place imaginable and I thought I had repaired all the leaks during the course of the winter.
Apparently not, as after recently test-riding the bike and parking it on the side stand, a short time later I discovered a fresh oil puddle under the left front side of the engine. It took me a while to track the leak back to this oil seal, which was about the only seal or gasket I hadn’t already replaced.
The part is still available from Honda, so a couple days later I had the new seal in-hand and it took only a few minutes to hook the old seal out with a dental pick and press the new one in place.