The flexibility of the Arduino platform makes it an ideal drop-in replacement for any number of out-of-production control and sensing systems, which in turn makes an Arduino or two a must-have in the toolbox of any engineer. A great example of this can be found in a project write-up from Jan Cumps on the business-to-business component supplier Element14's design challenge blog: using an Arduino Uno to replace the motor control and speed-monitoring circuitry of a vinyl turntable from 1958 - decades before the Arduino project was even a glimmer in its creators' collective eye. While Jan focuses heavily on the theory of what he's doing, his so-far seven-part series - scroll to the bottom of the linked post for the table of contents - is well worth reading as the perfect example of how to breathe new life into classic hardware that would otherwise be destined for the scrap-heap.
For almost a year I have a vintage turntable from Perpetuum Ebner at home. It's not mine. It belongs to someone that asked me to fix it. And it turned out that fixing the motor would cost too much. I asked the owner to collect the tt. That hasn't happened yet and the machine is collecting dust at my home. So I'll take the freedom to attempt a non-intrusive repair with modern components.