By a very scientific method of stuffing loo roll in the gaps between the window and the trim and pouring vast amounts of water behind the window, I think I have found where it’s getting in. It’s the top right hand side (if in the van facing the window). I did struggle a bit there as the bonding agent is rather tough to squeeze out of the tube with the gun. So I’m thinking I have nothing to lose and may as well try and plug it from the inside. I’m thinking of flattening the end of silicone nozzle, ramming it in and giving it a good squeeze. I appreciate this is a bit cowboy, but if anyone else has any ideas of salvaging this mess before full window removal, please let me know. I wasn’t even trying to cheap out with this, just really fancied working on the van myself………
. Lesson learned the hard way I guess!