I discovered I installed this incorrectly. The mount to the extruder is slightly offset. I reversed and no drag now. I probably did not read the instructions.

A 40mm fan from Maplins (UK high st supplier) which strangely had three cables, fitted a treat! I discarded the yellow wire after testing that black and red were indeed power and ground. All hooked up to D9 and it works brilliantly and controlled via the software.

Just printed a big piece with two 110mm horizontal bridges and it is 99% perfect!

Just getting into 123D Design which I think very good except for moving objects against other objects - not great as processes need to be repeated and offsets calculated and adjusted for measurements. Of course I may be doing something wrong.

Thanks to those that advised. Case Closed.

MakerFarm i3v 8"
E3d-v6 hotend
Hotend temp 225
Bed Temp 70
Translucent Green ColourFabb PLA
Slic£r 1.2.9
Mac 2.3ghz, 8gb ram
123d Design checked by NetFabb