Thanks.
Not your fault, but really not good from Microsoft on this. 3 years and a £900 piece of kit fails to do the most basic thing, without having done anything physical with it to instigate (it just sat on a shelf for a week after last using it, when it worked fine).
One very very unimpressed customer here. Really wanted to be impressed with this, and was whilst it worked, but won't consider touching the surface line again if this is how MS are going to support it.