Sears Craftsman wet and dry vacuums use a filter to prevent dust and dirt from escaping through the exhaust while the vacuum is operating. Cleaning the filter usually is a matter of tapping the top of the vacuum power head. Although the filter is cleanable, it's time to replace it when it no longer traps dust efficiently even after you've cleaned it. You can find replacement filters at Sears. Replacement is not difficult.
Unplug the power cord, and lift the latch locks under the handles of the Craftsman Wet-Dry Vac to unlock the power head from the canister. Lift the power head off the canister and place it upside down on the floor with the filter pointing up.
Twist the filter nut on the top of the filter plate counterclockwise with your fingers, and remove it from the unit. Lift the filter plate off the center threaded rod.
Pull the old filter off the filter cage. Slide a new filter over the filter cage until the filter rests against the bottom of the power head.
Position the filter plate over the threaded rod, and push it down until it is against the end of the filter. Thread the filter nut onto the threaded rod until it is hand-tight.
Lift the power head, and place it over the canister. Push the handle locks down to secure the power head to the canister.