Weller PU-2D Soldering Station

[Skywave]

Rob - if the tip is looking dark blue, that is normal for a #9 bit. That colour is simply the colour that that grade of steel acquires when it has reached its correct temperature. Your real problem is that a #9 bit is unsuitable for what you're using it for: in a word, it gets too hot for that job. Keep the #9 for when you need to do things like soldering direct to steel chassis and such like, where the heat-sinking capacity of the item to be soldered is large. A #7 is the 'general-purpose' bit for everyday soldering.

Al.