Need help with door glass

Replaced the rear channel. That went ok. I am replacing the "Tape" that holds the door glass in the lower channel. The old piece was badly deterioated and when I tried to put the window down, it would pull the track away from the window. I have the replacement rubber from Dennis Carpenter. Do I cut the piece the whole length of the lower channel? The old piece only extended part of the length. Also, do I need to use some type of adhesive, or will the rubber alone hold it in? The new rubber looks thinner than the old piece. Any tricks on getting it in and keeping it from pulling loose would be appreciated.

I cut mine about the same lenght as the channel. As for installing well I used dish soap. the window and rubber should fit the channel fairly tight and shouldnt pull loose. If it does you may need thicher rubber. Other fixes would be to tweak the channel a little so holds a little tighter. The last thing you could do is use weatherstrip adhesive on the rubber to help hold it in but that would be a last resort for me.