Upvc window unusual packers fitted

[Djwilliams37]

Hi
I am attempting to fix my windows in with screws as the previous owner thought expanding foam would be sufficient. The window however, appears to have some type of auto-packers fitted and I cannot work out how to release them. There is some type of sliding wedge on top of a red plastic piece

 

[Djwilliams37]

Solved it the exterior beading needed removal

 

[Djwilliams37]

I cannot find out how to get these exterior beads back on. The window has an internal gasket which I have removed in an attempt to get the exterior beads back in. The shorter ones are finished off square which makes pushing the long ones back not possible. The beads do not appear to clip firmly into place and I have tried fitting them without the window unit installed