The dial on my WD12X keeps clicking round?

Hi I need some help if anyone can?
I have an Indesit WD12X and the timer dial keeps doing one of two things, It either just keeps clicking round or it stops on the first part of the cycle.
I have tried re-setting the machine several times but this does not seem to work. If I move the switch manually the actual machine/program works and performs as it should it just wont "click" to the next part on its own. Having said that once every so often the machine does complete a full cycle on its own.