I am in the process of restoring a Marconi T26A which I bought at BVWTM Museum event on the 25th of March and despite it looking a bit sad it is now looking a lot better than expected.
Among other problems it had a round water mark on the top of the cabinet.
After a few unsuccessful cleaning attemps, I searched the internet for a solution and came across this video:
https://www.cnet.com/how-to/how-to-r...ood-furniture/
It took longer than suggested and had to increase the temperature of the iron a bit, but it worked!
I thought it may be useful to someone with a similar problem. I did a search, but could not find anything in the forum.