It depends on how comfortable you are working on it yourself, but if it carries real sentimental value then I think sending it to a professional would be a good course of action. A service is never going to be loads of money (sub £50), and they'll at least be able to say in advance if it's a gonner, new movement job, bit of clean - whatever.
There are plenty of decent watch repairers that are used/recommended by folks on here, and quite a few here who are very competent hobby repairers.