I sent the Spirit back to the UK service centre who agreed there should be no play in the plier jaws (it was probably about 0.5 mm but still felt a bit sloppy). Its now off on an 8 week journey to switzerland!
I'm slightly surprised that, considering the time taken to look at it in the UK and in Switzerland, plus postage, plus repair time they don't just replace it but at least it's being fixed.
In the meantime I've been using the LM Core which is a serious beast indeed - bit bulkier than the spirit!
Mark