ok as a prolong I will show you what i have done to the model so far.
The first thing was to inspect the flimsy bottom peace so it hadn't warped ore been damaged in any other way, luckily its was ok.
Next I loosely fitted the walls and did a test fit.
It was horrible.
After a initial miss calculation.
I started by gluing down the left wall section.
To fix the to long wall section.
I had to manhandle it a bit.
joined it together and glued it in to place.
Added the additional hallway section
And gave it a first coat of paint.
And this is how it looks to day.
To do list
Add additional walls behind Jabba and on the left wall to hang Solo.
Cover up seam lines.
Drill / file out the floor gratis
Texture the floor and walls and it should look fairly ok.