The windows were completely trashed by our silicone loving Previous Owner.
So we busted out our ghetto grinder. We actually have a bench grinder, but this lets us spin slower so we don't damage the aluminum.
We used 1/16" butyl tape to reaffix the window glass.
And a double layer of butyl putty tape to install the window.
It's not exactly square, but we don't remember if it was in the first place. At least it's probably water tight.