Helo Dave,
it seems to be fault coming from coolers.This fault can be occur due to dust and bad bearing of the fans. [http://Here|[guide|12842]] is the teardown guide and replace both fans. ifixit doesnt have required spares and [http://this|http://www.ebay.com/itm/Microsoft-Surface-Pro-1514-1601-Brushless-Cooling-Fan-KDB04105H-2309-/351405613222] one found on eBay. double check before order it with your model number.
Hope you could solve the fault your self
Cheers!