Ran into this one yesterday.
You have to firmly hold the spool with one hand or use the tool provided to keep the spool from turning...
Then turn the knob on the bottom of the Spool Clockwise (opposite of most nuts/bolts) to loosen. If you're not careful you'll end up with the knob in your hand and the nutt still tight. At that point you can use a wrench or pliers to lossen it.
I don't understand why they havne't developed an easier to maintain system like Weedeater uses.....
Ben
April 2008