It was, and still is, a fine antenna. The main problem I see is that it used flat line antenna wire (300 ohm) rather than the 75 ohm coax used on all televisions today. Changing the cable is the most difficult part of any update job, but then you would have to do it with a new antenna too. I would bet that after 41 years the old cable is shot anyway, at least the exterior part.
I think, but not sure, that parts are still available for it. I would be pretty sure that New Old Stock parts are around too. If you rebuild it, I would get the plastic parts which move the wings in and out, as well as the gear mechanism. They are (or were) all pretty cheap, but I have not re built one recently.