F26 error code mean pump drive failure.
Basically the control board is picking up a pump problem. Its not sensing it in the circuit of the washer.
Now theres 3 things which can cause this. Either an open circuit pump. Faulty pressure switch or the control board.
If you have a multimeter you can test the pump by disconnecting the wires and check for continuity.
Also you can do the same for the pressure switch. Just check across the contacts on the pressure switch and 2 of the tags should give a reading.
But if they are both ok the im afraid its going to be a faulty control board here. To be honest its more likely to be the control board but worth checking the pump and pressure switch first just in case.
If you need anymore info just get back to me.
Just wondering how you got on with the washer as the question is still open?