Trust me, I've opened and fixed quite a few. It's not anything I'd recommend to a lay user. Especially on older ones everything plastic cracks if you're not extra careful. But if you did manage to put your parents' clock back together all right, well, yes, you can save a bundle. And the leftover screws'll come handy in your next project!
Hey and everybody: don't forget to put a drop of oil to the cover hinges once a year!