[KevinH1990]

https://www.youtube.com/watch?v=g1N9TdLCFGo

This video should help. I think that there are two likely sources for your problem:

1. A failed bulb
2. A failed lcd

I think it is most likely the bulb because the display failed suddenly.

You can follow the procedure shown in the video to disassemble the cluster and replace the bulb. If that doesn't resolve the problem, the video shows the procedure for replacing the lcd. The de-soldering and soldering process required to replace the lcd appears to require some skill. You may need to find a speedometer repair shop to perform the work for you.

In the U.S., Palo Alto Speedometer and Hollywood Speedometer are potential repair shops. (I have not used them, but a search should reveal some posts from Porsche owners who used their services.) I expect that you can find a similar service somewhere in the UK.

Good luck.