They just don't make things that last anymore

What your really needing to pay attention too when you get in there is where all the allighnment bolts ect.. ect.. Because if your window was sealing tight before this happened
you do not want to lose that, if you do lose that then its a wack a mole pain to get it right again..
As far as the repair, It will be self evident when you get the panel off.. Might as well fix both sides since you say your having issues with the other one too..
Before you close it all up again, check several times the operation of it, slam your door check again then slam and check agin. check it with door open, check it with door closed.
The reason I say that is I have heard of, and can see it happening. You do all that work, going to the store or work a couple of times and bam wondow drops again..