Try this, on the bottom right hand side of the machines front should be a small circular cover. Unscrew this cover and remove it, there should be a white cross shaped plastic tap. Often this tap comes away from its fixing and it may be lying on the base of the hole, simply replace it so that the hole at the caps base is now fixed to the protruding metal bar pointing towards you at the back, it should click into place. Give it a spin or two to ensure its afixed. Im not sure if this is the problem but replacing this cap has fixed many faults with my machine.
Damien, May 2006