Outer Limits 4x4 Board

Well the door window seal disappeared one day and the window started to rattle if you had it anything but all the way up. I found it in the bottom of the door and found out about 1/4 of it had just vanished into thin air and the end was ripped.

So bought some new seal, but I can't figure out how to get it in. Durrrrrhhh.....

Is there some trick to it, I fit it in the channel, then try and push it past the glass but it's just too tight and it won't go any further ?

I don't have to remove the glass do I ?

Usually you remove inner trim and then the window.
Fit the new bailey channel and then refit the glass and door trim.
Jas.