How can I fix my Simpson Espirit 5.5kg washer?

The machine fills, but won't adgitate every wash. The dial continues to click through the cycle on the dial regardless of whether it's adgitating or not. Finally it will empty, but usually without spinning dry, or if it does, you need to put it through spin cycle at least once more to get a decent result. All the obvious things have been checked to no avail.