My OPS went at Cadwell yesterday meaning I had to miss the last session
It's a simple unscrew and screw in affair to replace. Just make sure you don't overtighten it, hey Antonye
The coolant on the left hand side is a split header tank as, believe it or not, is happening to me too. (Hang on a tick. You're not riding my bike are you?) Apparently it's a reasonably common'ish thing.