Cheers Jim.
I spoke to Rest Express this morning and top marks to them. They've emailed Mirka's details to me if the smell gets worse. They think it's just the smell of a new machine and they probably right, although I've never smelt this before on a new electrical machine. The best way I could describe the smell is spilling a drop of oil onto a hot car engine - a sort of burning oil smell. I've been using the sander today and its performance is absolutely faultless, so I shall carry on with this beauty and if any issues develop, I'll be on the blower to Mirka - it's on a 3 year warranty.
All good stuff.