u/nippledripple

Got this Certina from my granddad. It’s scratched and worn, but I really like the style of the watch!
I’ve tried to look it up, but couldn’t find the reference number or name of the model. I think he bought it in the late 70s or early 80s. Any idea what kind of Certina it is?
I’ve changed the battery, but the watch stops after just a couple of weeks.
Do you think a service is needed, and more importantly, is it worth it on a old quartz watch?