Second hand is best route.
When mine failed a few years ago I couldn't find one and
@Brian H gave me a lot of help finding an alternative. He even gave me a push button light switch - I think from RS but I can't find history at the moment. The problem we could not overcome was a low enough voltage bulb to fit the new unit. There is a permanent 5v supply to the switch but the pulse signal for the LED was only measured at ~.1v.
I ended up with a compromise using the old one as an indicator only and the new one as a switch only. I had spare plates on the console so they have sat fairly neatly side by side for the last 4 years.