My 12 year old hoover six 1100 door won't open after the wash cycle has finished. It will however, if I unplug it and leave it for a few hours. (I run the dryer as well, don't know if this helps) Why is this and can it be repaired, and at what cost? Someone suggested it might be limescale on the pressure pot (huh?) and I could clean the tubes myself! Really, how?