The replacement filter was a simple swap for the old one, so lid off, remove old, replace with new. No pictures taken from that.
First insert the screws in the holes as they are otherwise very difficult to get in:
Old unit in place:
Old unit removed:
Where the old one used to be:
New one in place:
Use a small screwdriver to fix the top screw first as you still have movement to get your hand in. Use the long screw driver for the bottom and side screw:
Unit installed and seen from the side:
