Electric window popped out of frame and seals Octavia Mk 2

A couple of days ago, when winding the offside rear electric window up, it squeaked loudly up into position, then wound itself down a bit again. This happened a couple of times but it eventually went back into place. I should have left it...

...but forgot and put the windows down again the next day. The window pane did not align properly and ultimately ended up at the angle shown in the attached picture. The kids were not impressed with the window rattling and threatening to fall out on the M25. As you can probably see from the picture, the window almost lifted completely out at the front, while cutting slightly into the rubber sill at the back.

Once stationary, I was able to let the window down, then back up (reseating the window into the rubber seal and applying pressure to window as it rose). Does this mean the motor/regulator is ok?

Looking at the YouTube videos I get the sense that it is beyond me (why is there is a riveted internal panel in the door that need drilling out?!). Just looking to see if anyone has had the same experience and might know what the issue is? I read something about a known issue on the Octavia around plastic locator dowels breaking, and there is a cable that snaps as well.

Grateful for any thoughts.