Chosen Solution

So, my E key on this machine is no longer always working when pressed anywhere other than the centre of the key. I think it might be an issue with the key itself as when the key is removed I can press the rubber button multiple times and the key types fine. I have never diagnosed an issue with a key switch before so what would I look for in trying to resolve this issue. I could order a new key with switch but would like to try fixing this one before I do that. Can anyone offer any advice?

Sounds like you have either a bad keycap or worn scissor mechanism. Here’s a good source BookYard UK: Keycaps and key parts