I'm having problems with the wipers on my Alfa Romeo 156?

I own an X registered 2000 Alpha Romeo 156, when the wipers are on the intermitant setting the motor does not appear to have the strength to move the blades across the screen + on the normal setting when switched off the blade's do not return to the finishing position.

I've read a number of articles which tell me to remove the motor and clean it, but to be honest I'm a bit thick and whilst I've removed the motor and all the bits attached to it I'm not sure what I should be cleaning and how !

Can anybody help ?