Are you a wooly bully?

[The Great Oz]

Thanks John, I had to slap myself for missing that an installer was to do a restretch.

Absolutely lift the carpet since you have the chance. The backing often tells a story. If say, there's dark discoloration or mold at the stained area near the window you know there was a prolonged exposure to water and there may be other structural issues in that area. The same with the circle spot; the back could show the prior location of a potted plant; the continued overwatering of which would let a lot of tannin seep into the carpet.

Also, if you don't have one go pick up a pocket microscope. Looking into the base of the tufts with magification might tell you something. Could be a build-up of potting soil, Host, baking soda...

 

[Bob Foster]

Carpet definitely had previous water damage. The big circle is where a potted plant was and there is a bleached out spot right under where the pot sat the someone tried to remove something before. I peaked under the carpet by lifting one of the registers and there is previous damage.

They knew this and are totally accepting of any outcome and are grateful for my efforts and return trips.

Encaped only the affected areas with a mist of acid rinse and a light encap of snake oil. If it drys out OK its a keeper if not its a tear out. And they are good with that.

And this ordeal is exactly why you charge appropriately to work on wool. The original price was $336 for a standard sized dining room with a step down into a basic sized sunken living room and I lost money on this job considering the multiple trips.