It was probably worn from someone's hand resting on it and adjusting the knobs a gazillion times over the last 45 years.
You can repaint the whole piece, try and touch up that area or just leave it unless it really bothers you.
There are some nice lines to tape off of and it looks like you can go around the lettering.
You can use a scuff pad instead of sandpaper, it's a little more forgiving.
As far as color, you'll have to do your best to find a close match unless someone chimes in here with a color.
Look at colors online or take a good pic and try and match it to a can at a store.
If you paint that whole top part and tape off around the lettering, a slightly different color won't be noticed as much as if you just touch up that part.