I decided to use new screws, these stainless steel ones will do just nicely.

Two each side are needed. Once fixed the bottom and sides can be removed, the sides are then marked for length.

  
To cut the sides to length a chop saw is handy to get good clean cuts. The small piece was a test cut, the next one was to the correct length.

On this blind it calls for a hole in the side piece 34mm from the bottom. A pilot hole is drilled first...

  
...followed by a 6mm drill. This allows the blind to locate for closing.

  
Sides installed and the bottom is screwed in place and the supplied endcaps put over the fixings.

  
If the blind is greater than 80cms wide an additional fixing is recommended. In this case a pilot hole drilled in the middle.

  
And a stainless steel screw to fix. Makes it secure.

  
The blind is then checked for correct operation and the curtains refitted.

  
Here the blind is a notch down and the flyscreen brought up and attached to it.

  
A view of the nearside window blind fully closed. It cuts out a great deal of light.

  
A view of the offside blinds. I think it looks smarter than the originals.