Do you want to have the piece restored? If so, will suggest you take it to a furniture shop that builds and repairs furniture. There should be someone in your area who is capable of doing that.

It's mottled antique brass. What do you mean by it needs some maintenance?

As you can see in the photo, there is an area where something must have spilled on it and there is no 'mottling'. Also, there are areas where the lacquer seems to be damaged. I bought this around 1986.

I remember this finish from that era. My mother's friend had a very eclectic style and accumulated interesting pieces. I found some photos.

All, which look like the top of your coffee table, seem to be a special finish on glass, but on brass frames or stretches, to look like mottled brass and have value....if you don't repair or damage with a strong cleaner.

https://www.antiquesboutique.com/antique-coffee-tables/maison-jansen-glomis-glass-and-brass-coffee-table/itm230238

Are there an identifying marks on your piece? Prices seem to run over $1,000.00.

After posting this, I did a deep dive searching the internet. After owning this piece for 40 years, I've finally founds something out about it; made by Mastercraft and German artist Bernard Rohne made a career of this signature acid-etched brass finish. I found a similar table for sale on 1stdibs. So I've learned that the technique used is 'acid-etching'. Now to find a contractor to help.