This is a really old electromechanical device that I bought from a junk market (The Barra's) many years ago. Tonight I spontaneously got the urge to add some internal illumination using simple generic ebay LED strip.
It turned into quite a task with the bulk of the time spent removing hacked wiring internally and cleaning parts of the mechanism, then adding some new wiring and an external 12V jack. Then it got reassembled and the new LED tape measured, cut, linked and then carefully installed in a manner that makes it completely invisible from the outside of the case. I also added a diode in series with the 12V tape to dim it down a bit (From 850mA to 650mA total.) The result makes me wish I'd done it sooner. It truly looks like a working museum exhibit now.
(It's a Gents Pulsynetic master clock used to run all the clocks in a building in sync.)