What is the gadget called that carpet fitters use to estimate area of a room

Measure the length and width of the room (in feet) then just multiply the two numbers to give square feet.

If you are referring to the front nozzle area, Hoover has made a tool called a nozzle cleanout tool # 39514003

I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_b96ba3f038cf317c

Hey, the mold ring is showing the carpet is now clean in comparison to the rest of the room.

You may want to have the rest of the carpet cleaned using a BISSELL deep cleaning machine or by calling a professional.

go back thru the steps making sure that the square plastic airflow tube is properly installed

If you're renting your home, call the landlord and let him have it taken care of.
If you own your home, the best thing you can do is to call a carpet cleaning company with a truck mounted machine. They still won't be able to remove all the moisture, but will get it dry enough for the next step. If you feel this would be too expensive, rent a "steam cleaner" from a rental place, or store where they rent them, and go over your carpet several times with this.
After the water has been vacuumed up, you'll need to lift carpet and prop it up enough to allow a fan or two to be placed so it will be able to blow air on the bottom of the carpet, as well as the pad. Raising the temperature in the room, or placing a heater that will blow warm air on the carpet and pad will help dry them faster.
Ensure origin of leak is fixed.

The seam problem could be an installation problem. It is important to pattern match any carpet with a pattern. If the carpet is a plush carpet, the seams should not be invisible, but not unsightly. If he carpet is a frieze, the seams should be hard to find. Any variance from these norms could mean a redo of the seams by a talented carpet installer. In a large room such as yours seams will never be invisible.
Good Luck, carpetguru

It is possible that the height adjustment on your Kirby is to close to the carpet,which could account for the problem you're having.The correct height adjustment for your Kirby is this-Lower the height adjustment down until you hear a change in the sound,then adjust one more click down.The Kirby is at the correct height for cleaning.If the carpet is different in another room,adjust it the same way for each carpet