This is a hobby of mine.
I learnt a decade or so back at an evening college course.
Many colleges do it and its a fun hobby to learn. So might be worth a look.
Not only learning to repair and maintain clocks/watches etc but also how to treat/restore the cases.
The course I attended was a couple of terms each year. A small number had been going for a number of years and treated it more like a small club and working with the tutor to give others good help and advice too.
I just did it for two years, as I felt I had learnt enough to be proficient and gained my qualification certificate
mind it gets you good contacts and have since wanted a few small parts made up or sourced and they duly supplied.
I love clocks and have all sorts of mantle clocks around the house that I have cleaned and restored from.
After time they do become dirty and a good clean is all that is needed. Not failed with ones I have acquired yet.
Would encourage you to ask around as Mantel clocks are not too much work to clean up and revitalise and there are plenty of hobbyists, retiree repair centres or even via a local college course.
Afraid I do not do it as any kind of offering.