Click on the thumbnails for an enlarged view.
Peel off the plastic feet and remove the four screws.
The orange button and spring tend to go flying off...
Then remove the four screws which hold down the motherboard.
Unscrew the six bolts that hold the back panel on.
Back panel now comes off easily.
Here's the stock back-panel.
Turn it over so you're looking at the inside.
Using a file, rub off the tops of the four rivets.
You don't have to remove very much (one of four is done here)
The fan can then be removed by prying it gently.
Then just lift the fan off.
... this leaves the back panel empty.
Align the new fan by the lower left hole, and mark the upper left hole.
Drill a new hole (since the new fan is larger in diameter).
Two screws suffice to hold the fan (or just glue it...)
To make the fan fit, you have to cut the plastic a tiny bit.
Then it should fit together very nicely.
Here it is with everything put back together.
Here's the back panel with a big chunk taken out.
A bit of filing to get rid of sharp edges (avoid whistling)
And here it is all assembled.
With this set-up, the temperatures in my winder are lower than with the original fan.