Re. Hotpoint WDD960 Washer Dryer.
On Dry programme, clothes come out hot and steamy – usually – not always. Intermittent fault. Sometimes does not pump out.
But Dry works ok when set up as continuation of Wash or Spin programme.
Dryer needs a few things to work properly. You have heat so the element is ok.
You need airflow. Over time the condenser and or the fan can clog up reducing and ultimately stopping the air flow.
Water. To be able to condense the steam back into water the machine uses a trickle of cold water. If this valve does no open for any reason the clothes will be hot and steamy but not dry
short answer to your question is I don’t know why it works on one but not the other
one question is where did you get the new board from ?
reason I ask is these days new boards are blank and have to be programmed. If you buy a second hand board off Ebay even with the same model it may have different software installed
I have also merged your posts as duplication does not make sense