I have a back door which is double glazed.the top panel is glass and the bottom panel has a cat flap in.I want to take out the panel and get a new one without a hole in it.Just how much force should I use to get the beading off.I have tried levering a wallpaper scraper behing one of the beads but dont want to snap it.Whats the best tool to use,how much force should I use and which bead is it best to start on please.Oh its interior glazed the beading is on the inside