Dad's Old Seamaster De Ville

Correct, the movement is circa 1964. If you show photos of the bracelet, you may get some information about it.

By the way, I think it would be a nice gesture to show some photos of the watch, so we can appreciate it, instead of just showing the inside of the case-back so we can give you the information you want.

I would love to find a table of American case numbers.
I also have a KL6292 front loader with a 550 movement. (Or so my notes say. Now I may need to check it again. The link above gives 560 as a caliber) The notes indicate my movement has a 2889xxxx which would put it at 1969. As far as I know this is what I got 24 to 30 years ago. I never got around to putting it on a strap. I doubt I ever cleaned it either.

These movements are easy to work on. Parts are somewhat avalable (If the USPS ever bothers to deliver them.) Should not be too dificult to find a repair person for it.

That is a good price for a service. 400$ would be closer to what they need to keep the lights on. That is also close to what the 505 I got on eBay, with donated parts and a 30 year old dial I have will cost me. And I have not even got to the case for it.

If it was not for the liability I would love to have been a watchmaker. So few realize how much insurance and such is needed. I tired repairing watches for friends. They got mad when I replaced the yellowed crystal (what was rusting the hands with a clear one.) You just can not make people happy in this day and age, where the watch needs to look like a scratch free AI computer generate rendering.

I am glad I learned some of how to service 30 years ago. Even then, they wanted 'young' people who do things the 'factory' way then complain when people are not happy with the work. It takes a strong person to put up with that sort of criticism. It is not about the work. It is about running a business.

Anyone with the right mindset will have more work than they can handle. So when one does find someone, expect them to be busy.