I have dismantled my distributor. After some initial cleaning, it really looks like that is all it needs. The BALL is not perfectly spherical, but it does roll around. Maybe a flat spot or two. The upper plate where the ball sits is shinny. Lower plate is shinny where the upper plate touches.

What are the thoughts about replacing parts or just a good cleaning and re-assemble?

Photos below:

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Clean and regrease

BTW: the counter weights under the plates look dry. I don't see any gunk or issues here, and I don't want to take them apart. Do they need cleaning? Maybe some brake cleaner and a drop or two of oil brushed around....?

You've got the right plan. Very few new parts are available. Lube it so everything moves nicely, and then put it back together.