I want to replace the top panel of our garage door to one with windows. It's a Wayne-Dalton model 9100 door, standard 2-car garage sized. The door, and springs, are 2 1/2 years old. Two companies have told me I will need to replace the existing spring with a stronger spring when I put in windows. Is that correct? I just don't see that the windows will add so much weight as to require a stonger spring, especially since it's not that old. Am I wrong?

Hi all, Making my first post here. I recently installed a new Chamberlain 1/2 hp belt drive unit on my garage. It replaced an older chain drive unit that the sprocket failed on. I've noticed when opening the garage door trolley is as smooth as can be. When on initial closing the "boxcar" off the garage door J bracket bounces on the trolley on the rail. It bounces maybe two or three times and then smoothes out. Is this normal? No binding on the track, garage door is balanced(new torsion springs last winter). I attached a video as well. Thanks in advance! https://youtu.be/BeZmCcNpTqM