Good job on the coupler and agitator cam! Way to go!
Now for the grinding noise... I assume that it wasn't making that noise before you worked on it, right? (except for the noise it makes when the coupler has failed. It make a kind of grinding noise, too.) So I'll assume that this is a different
2 things will cause this in "spin".
1.) Something is caught between the inner and outer tubs. Since you've had the cabinet off, you know that there is a perforated steel inner drum (the one with holes in it) and a plastic outer drum to contain the water. I've seen nails, paper clips, etc... get through the holes of the inner tub and get caught there. When the unit goes into spin, the object will spin along with the inner tub and rub the outer tub making a scraping/grinding noise.
To find out if this is the problem, remove the agitator again... yes the entire top and bottom portions of it. Now CAREFULLY inspect the inner tub and look for anything that may be stuck in the holes. It'll be small, so use a good flashlight.
2.) The "drive block" has cracked/broken and allowed the inner tub to drop to the point that it's grinding on the outer tub base. This one is a bit more intense than the fix above. If you would, please verify that there's nothing in the inner tub before we proceed to the next step.
Note----> I don't doubt that you can't handle the next repair. It's just that I want to eliminate the simple stuff before moving to the more complex stuff.
Let me know what you find, OK? Also... BEFORE you remove the agitator, look at the distance between the bottom of the agitator and the base of the inner tub. Use your finger for measurement. You should NOT be able to fit the tip of your finger between the two. If you can, write back 'cause then we'll be going into the drive block (#2) repair.