Hoover 1300 logic washing machine?

I am trying to find out how to remove the pressure vesel on the back of the drum of this washing machine. It is a small white vesel, and has an orange tube connected to it to the pressure switch. I have tried to remove it, released the two cilps and tried to pull it out, but it will not come out, tried to twist it too, but still will not come away from the back. Is there a reseason it will not come away, so I can clear the blockage. Can someone please tell me how to remove?
I have tried many times but still will not remove.