When I had to remove the front screen I found it easy to peel the rubber from the frame on the inside. I did this around the top and sides and then rolled the screen forward finally carefully lifting onto a blanket. With this method there is no risk of scoring through the galvanising when cutting the seal and you save the rubber for re-use, if required. When putting the screens back in the fitters will prefer re-using a serviceable rubber seal than using new. I believe the insert is hard to source so care is needed when removing.
Steve
Steve