The LBS Idea sounds like the plan!

But for curiosity and info's sake, I will continue until I can make it to the LBS. I am not at my shop right now but the notches are about a 1/4 inch wide and 1/8 inch deep. They are recessed in the ring they are cut into. The ring they are in is threaded on the inside and outside. The inside threads screw onto the hub. The outside threads are what the cogs are screwed onto. If you look at the back through the flanges of the hub, you can see the bearing /race access plate. So to service this freewheel you would need to take it off and service it through the back. This freewheel looks like it is backwards from the Maeda/Suntours I have.

The ebay seller said that the hub/wheel combo came from a 70's era St. Etiennes bicycle. The Mavic rims have 0973 stamped under the SPORT so 1973 might be the year. The freewheel is probably french but you never know.