Recently changed the plugs on the car and while they look clean the #4 plug ground electrode looks bleached in comparison. Oddly the bleached effect is mainly split along one side of the electrode, while the other half resembles the other plugs.

Any thoughts on what this might be indicating?

 

Hard to say. I'm not really sure that what we're seeing represents a correctable fault

Perhaps a bit lean on that cylinder?

Let's hear what others have to say

Cheers
DD