How to pop back of door glass into channel?

[vikingsandpintos]

Among other projects on this truck, 67 C10, I am changing the window regulators.

I have read the various posts on how to do it, and have gotten it all apart. I have the new regulator installed, and have the doorglass rollers in the correct guides, but can't seem to pop the back edge of the metal on the bottom of the glass into the back channel towards the door latch.

When I took the glass out, I didn't really notice how it came out, and don't see any trick to get it back in other than brute force, but afraid to try that! lol. I haven't seen anything about it in the other threads. What am I missing here?

And while I'm at it, what is the best lube to spray/apply, and where, to make sure the window goes up and down good. I assume on the rollers and guides themselves, should there be anything on the edges of the glass, or will that smear on the glass? Thanks! Earl