3rd door window problem

I inherited a 2000 GMC Sierra extended with the 3rd door on the passenger side.
It was making noise so I took some soft brushes and cleaned all the rubber then washed it with a soft cloth to get the rest of the ten years of dirt off.
The results are, it now makes a lot more noise.

My question is did that black closer latch actually snap into place when it was knew to pull it in? This one does not latch but has no visible breaks anywhere.

Second, is there a quick fix for this other than replacing the window?

Third, should I just run a small bead of black silicone rubber around it and let it go?