Below is a picture of a stain on my carpet from some something, I'm not sure who spilled what. I only know it was dry and set when I found it.
So before shampooing the carpet I got out my bottle of Fulsol Spray (mixed 3/4oz Fulsol added to water to make 1 quart of spray cleaner) and sprayed the stain. I then used a brush to scrub the area and get the Fulsol into the carpet fibers.
I let it set and work while I got the carpet shampooer ready to go.
Here is the same area after shampooing:
You can find them both in the Kitchen products area on my Fuller Brush Factory Direct page.