The livescribe OLED-Display is cheapest cr** - not perfectly sealed, oxygen and especially atmospheric humidity can rapidly degrade the organic light-emitting materials inside. Livecribe has proven :(
I got my pen replaced by livescribe (warranty) just to see it fade shortly after the original warranty period expired.
You can disassemble the Pen, but i found no replacement for the display so far... I can't imagine that this is a proprietary part made just and only for livescribe, so somewhere in this world there must be an OEM part. Maybe someone else has an idea?