Hi, probably best to have two people doing it; one working from the inside pulling the cord & one outside pushing the glass in. I found the easiest way is to put the glass in the rubber (. & chrome trim if fitted) wrap a good strong cord around the outer lip of the rubber, use plenty of soapy water, pick a side to start & go from the bottom of the centre post around to the top. I also used one of our cutlery knives to run around the inside lip of the seal to help it along in places, gave it a few brave thumps to get it seated in, swore a bit & spent about 15 mins doing it. If you' re refitting old glass it will be more brittle than new so more care needed. Hope this helps, cheers Ju.