Do not take it apart. All the pre-1990 SA hubs were oil lubricated. No grease needed. Ordinary bearing rease put inside the hub will bring significant problems. Open the little oil port, put in a squirt of light oil (SAE 10/30 is ideal) - no more than a teaspoonful, and flip the oil port shut again. If it works great as you say, that is all you need to do. If you do this about every 100 - 200 miles, it will last forever and work just like it does now.
Only take the hub apart of you have GOOD reason to suspect that something is wrong, and before you do anything, make sure that the supposed problem is not with the cables, adjustment, or shifter on the handlebar. These hubs are usually bomb proof (I'm assuming that it is a 1970s AW hub).
Enjoy it. There are few better things on a bike that an AW hub that hasn't been abused. SW hubs were terrible - they never worked properly. You can see what model and year the hub was made by looking at the engraved information on the drum of the hub. It might say something like AW 69, meaning an AW hub made in 1969.