The companies who make the components may have merged, gone out of business, switched to manufacturing something else, etc. That's the real problem -- you can'

The companies who make the components may have merged, gone out of business, switched to manufacturing something else, etc. That's the real problem -- you can't source the same components you did, and in order to work around those problems you need people with a deep knowledge of the whole system who can figure out how to resolve that.