Older stuff generally had poorer tolerances and in some cases barely worked. However when it did it was easy to fix and was generally designed with a large marg

Older stuff generally had poorer tolerances and in some cases barely worked. However when it did it was easy to fix and was generally designed with a large margin. Nowadays we make things with a lot more precision and the mechanics will go a lot longer without needing repair. However if anything goes wrong the whole thing needs replacement as it's not designed for repair.