Hi,

I will say it’s best to remove the mat with the carpet and inspect the bottom. The coolant will rot the rubbers below the carpet.
Trouble is, getting the rubber mat out intact and it not cracking or crumbing.
Bending it all backwards was not an intention to be done at this age.
The seat removal idea is best as you will be shocked with what you find under them. Wood shavings (?) or Especially any spills on the brake/switch console. 😵‍💫

Plan on being gentle and cunning while lifting it out. Slide you hand under it gently to feel it out.
The older the car the more likely the above will happen as the older cars used butyl to stabilize wiring harnesses down tighter in places. That stuff oozes into the foam. Surprisingly the carpet can get shot of it.

The coolant that is slightly oily and has probably is already gotten on the backside of the windshield.
It promotes streaks and smears when cleaning.
You will need a “stick on” window cleaner to break it down.
I recently had two windshields replaced and my installer used an aerosol “SprayWay” product. They packaged about 2500 different products.
It is obtainable in Walmart stores.
It sells reasonably for @ about $3 a can in the automotive section.
Mine and his were scented so don’t pay more for less. Elsewhere the prices are crazy!
It says it’s used to do more than glass and leaves a nice fragrance for a short while.
I have been an Invisible Glass fan but with all things considered, it beats them. IMO.

We are enjoying your posts. Keep them coming!

Phil