Have you tried typing "plasma parts" in google ? Here is an example and the second or third hit down should be fine for you it's the one not for television repairs.
If memory serves there was a seller on eBay that was selling spares but carn't remember there name but they were near lancaster
Mini's are hard to farm they run away a lot! If memory serves there was a seller on eBay that was selling spares but carn't remember there name but they were near lancaster