I'm new around here and have a question about headliner cleaning. Everything I've found says it's a fragile headliner that can sag if cleaned incorrectly. The car was bought a few months ago and I have done everything in my power to clean the interior of the car. The smoke smell still lingers however. The only thing that hasn't been touched is the headliner. I'd really rather not pay the $500 for brand new headliner. I'd really truly appreciate some tips and tricks on what to use on the headliner to hopefully eradicate the lingering smoke smell without completely ruining it. Any help would be great!