Lowflyer
I did replace the windscreen in my 71 4/4 a number of years ago. I had obtained some windscreen rubber stripping from one of the dealers and with the use of a couple of sash clamps and some rubber lube and some pieces of scrap packing wood carefully eased the new screen into position making sure you leave a excess of stripping either side. trim the excess but not too short and then fit more stripping and fit the bottom rail again using the clamps to force the bottom rail on. You have to make sure the screws either side are not too long, label them when taking off. I have heard of others using silicone sealant instead of the rubber stripping but that does not appeal to me. Would be great fun replacing a screen when silicone sealant has been used.
Doug
From deep deep down under