Bluetooh is still not working with my speakers. But it is working (a bit unstable) with a new mouse. . I have now tried connecting my two speakers to my Lumia phone via Bluetooth and found they work OK --- so it is clear the fault lies with my PC, which will pair with them and usually not connect, or if it does (ocassionally) the sound still comes from the PC.
The Bluetooth drivers which are from Microsoft and dated 2006 (as are many drivers on this machine) are declared as up-to-date. So what is there now left to do? The speakers did work with the PC until a few weeks ago.