Thanks for the various advice guys. I have eventually found the T300 setup menu, thanks Robby.
I think that I have found the missing FF problem, but time and several re boots will confirm that all is sorted. The old Logitech Gaming Software had not fully "uninstalled" and I discovered that there was an element(s) still running in the background via Task manager. It looks like the basic Logitech profiler was initiated at PC boot and it was grabbing the resources before the Thrustmaster?
Now I have fully uninstalled and deleted all reference to Logitech, even though I am still running the shifter and 3 pedal Logitech setup for the moment. But these items are running via Bodnar connections, so actually are no longer dependent upon Logitech software.
FF now working in GTL, so I just need to adjust wheel settings to my preference over the next few days and learn how to drive again
@Christian
Initial impression of the T300 is that it has a much smoother and heavier action than the G25, but I think it will take a week or two to tweak all the settings ( degrees of rotation/FF levels/sensitivity etc ). I realise now just how worn/broken that my G25 was, so the difference is probably bigger than if I compared a working G25 to the T300?