Tailgate glass problem

[eighteenninetytwo]

Was just prepping the 75 for bodyshop and was taking out the inner and outer window seals on the tailgate (this is a new tailgate i scored which hasn't been fitted yet). I notice that on one side (left as you look at it when attached) the window is NOT in the guide channel and it won't come all the way up. What are the tips and tricks for getting it back in? ARE there any ways of doing it without dissassembly?? i have exactly two days before the truck goes to bodyshop so my time is limited unfortunately.