It appears to be a Cyclops due to the 12 mark
If it has some value I may keep it as a momento of years past.
I don't understand this bit.
It definitely has value, both sentimental and material. It uses a one piece case (monochoc/Unicoc) and must be opened from the front with the correct tool.
A missing crown is common as these use a "split stem".
It will be a nice keeper when sympathetically serviced and put on a leather strap (as it would have originally come with).
This is a cyclops- a magnifier in the crystal over the date window to better see the date. Your watch does not have it. Most collectors don’t like them. But as you age you can appreciate seeing the date.
Any recommendations for an honest service watch guy?
You will pay about $600 USD for the restoration