Static or slubs? If it seems dry and brittle--easy to snap just by pulling it with your hands--throw it away. If it's still strong--I would run a couple beads of Sewer's Aid down the sides of the spool. Let it sit for 30 minutes to soak in and then try again. Another thing that some people have done is place a piece of sponge that has been sprayed with silicone spray somewhere along the thread path. It basically does the same thing as Sewer's Aid and it helps tame some of the more squiggly threads.