I had a leak in one of my tall vertical windows in the garage. I ended taking all the screws out of the inside frame and popped the window out. I found that there was a section that lack a seal. I bought a new seal from Lowe's (cannot remember how wide) and re-installed the window, no problems since. If I did it all over again, I would have used Butyl tape...
TV: 2015 F-350 DRW, CC, 4x4, with 14k GVWR package, 98 gallon TransferFlow Aux Tank, Timbren Shocks
TH: 2014 Voltage 3950, Sailun S637 all around