Just a note on the extruder cooling fans.
Alas one of mine failed yesterday after only two weeks of use. I thought that it might have been a broken wire problem - given the number of times I have disassembled my extruder - but no, it was a definite fan failure.
The cheapest replacement that I could find on the web was from
here . You need these:
ADDA AB4512HX-GD7 cooling fans
The fans identified earlier are incorrect. Those are axial blower fans such as you might use on a computer CPU whereas we need side blower units that discharge the airflow sideways into the printed ducts.
I bought two, just in case !