Guys
I had exactly the same symptons with my Wren 44, when I rolled inverted the motor would cut after a few seconds. Believe it or not the cause was the rpm sensor magnet had become demagnetised and in the inverted position the difference in the earths magnetic field was enough to cause a spurious rpm reading and shutdown. The fix was to remagnetise the sensor by taking a strong magnet and moving it in a certain pattern at the front of the turbine. I felt like a bit like Merlin the magician doing this but it worked and I have not had the problem since!
Of course if the Falcon does not have a magnetic sensor this is not the problem and I aplologise for wasting your time!
John