Thanks to all who came with an advice. I found a place where someone has an experience with this. They use a product (forgot the name), it comes in as a tape, which they place over the channel in aluminum tab, then place the glass edge over it and with two blows with a wooden mallet they drive it into it. For that you have to have the aluminum part in horizontal and the glass in vertical, something I canít do with window in the trailer. The second option they suggested is the silicon. I will look into Loctite, thanks Bob. Unfortunately, the ambient temperatures are now well below +5C, so I will have to do it down south, if I ever get out. My vehicle is only a front wheel drive.
It is going to be tricky in how much of the glue I should put into the gap. The side near to the stationary part of the window is not accessible to remove all displaced material after I push the aluminum over the glass.
The 3rd option is to buy a small vacuum bell just for sliding the window open, to push it closed is not a problem. Iíll have to find out who sells the stuff.