Hi Dr Kee
Before i mention the obvious, remove the gas and replace it with a new mix.
If it continues to spin at idle, then we need to have the carburetor adjusted at a service dealer.
Altitude and change in the weather can affect the performance of the engine.
I apologize for the inconvenience and hope this will be helpful.
http://www.weedeater.com/node6506.aspx
Sicerely Peter Brisette
Husqvarna consumer support
Adjustment of the idle speed
Before any adjustments are made, make sure that the air
filter is clean and the air filter cover is fitted.
Adjust the idle speed using the idle adjustment screw T, if
it is necessary to readjust. First turn the idle adjustment
screw T clockwise until the cutting attachment starts to
rotate. Then turn the screw anticlockwise until the cutting
attachment stops. The idle speed is correctly adjusted
when the engine will run smoothly in every position. The
idle speed should also be well below the speed at which
the cutting attachment starts to rotate.
Hope this helps
Adjustment of the idle speed
Before any adjustments are made, make sure that the air
filter is clean and the air filter cover is fitted.
Adjust the idle speed using the idle adjustment screw T, if
it is necessary to readjust. First turn the idle adjustment
screw T clockwise until the cutting attachment starts to
rotate. Then turn the screw anticlockwise until the cutting
attachment stops. The idle speed is correctly adjusted
when the engine will run smoothly in every position. The
idle speed should also be well below the speed at which
the cutting attachment starts to rotate.
Hope this helps