Why doesn't my portafilter valve automatically open?

According to partsguru.com, the Saeco Gran Crema portafilter valve automatically opens when the pressure reaches 10 bars, moving the handle to the left and allowing the espresso to pour out:

"The pre-infusion delay valve in the Gran Crema portafilter arranged with an over-ride spring that holds the Portafilter handle pulled all the way to the right. As the pump pressure builds up to 10 Bars, it forces the spring to yield and push the handle back about 3/4" to open the flow of espresso through the coffee grounds. The Gran Crema Portafilter (Saeco Part.No. 226550850) opens automatically as the pressure to pump water through coffee increases. In the Gran Crema portafilter, the handle over-rides a spring and stays when pulled all the way to the right. When the pump starts, the pressure builds up inside the Portafilter and forces the water exit by pushing the handle slowly to open the passage. The handle grip can be seen moving to the left as pressure builds up allowing the dissolved coffee elements to flow through the coffee grounds and collect in the cup."

Is this an accurate description of how this portafilter operates, because mine has never done this. I have examined the parts diagram and I definitely have the Gran Crema portafilter because it has a check valve. My handle does not move automatically, I have to manually turn it to the left to open the valve and allow the coffee to flow. I'm able to pull two shots with a 20-25 second pour (valve closed 5-8 seconds for infusion and then open the rest of the time until shot glasses are full).