If you decide to use RTV be sure to use automotive RTV. which does have acetic acid (smells like vinegar). The regular type will cause rust. To center the glass you can use the cardboard that is on single edge razor blades or any thin cardboard you might have. Just fold two or thee narrow pieces it to the thickness you need to keep the glass centered then slide it in with the glass, The lower door channel can be installed the same way. Just be sure you use something to center the glass, and Lord help the next guy!
John
