Rear window channel

My rear nearside window wouldn't go up or down and on investigation find that the glass has come out of the channel that holds it to the door.
I'm loathed to buy a new channel at almost £30 delivered.
Is there a definitive way to put the glass back into the channel and have it stay there.
Took the door apart and re-attached the channel but after a few cycles up and down, its done the same again.

Its No. 7 in the photo (and the wrong door but its the same part)

Had a rear door window glass come out of it mount . I used a little bead of black auto grade silicon . I also found a few drops of 3:1 oil on the side edge of glass helps the window glide up and down in its frame seal . They do get a bit dry and make the glass stick when closed

crimp the channel tighter close the gap up.
then use water to knock the channel on . dont use spray oil etc

Think its sorted (for now)
Took the rubber out of the channel, cleaned both up and refitted, tapped the channel with a copper hammer and then crimped it tighter with mole grips, all the time praying that the window wouldn't break, seems pretty snug in there now and all back together again.

My front passenger side was similar - the channel was rotted away. I made a couple of little brackets out of some sheet steel and bolted them on then stuck it all together with silicone. Been fine for about 3 years now.....