Place chicken in 7-qt. crockpot and cover with water.
Sprinkle very generously with salt and pepper.
Cook on high about 6 hours until chicken is cooked thoroughly.
After about four hours, add carrots, celery, onion, parsley and salt and pepper to crockpot.
Continue cooking an additional two hours until chicken is done.
Remove chicken from pot to debone.
Add an additional quart or two of water to the crockpot – enough to bring the chicken broth level to about 2-3 inches below the surface.
Carrots and celery should be fork tender by now.
Add fettuccine noodles broken into fourths.
Cover and continue cooking while deboning the chicken.
Debone chicken.
Remove fat, gristle and bones and discard.
Shred remaining chicken pieces into bowl. Mine equaled about 8 cups of shredded chicken.
Add shredded chicken.
Stir into crockpot and continue cooking until noodles are cooked through. My noodles took about 20-30 minutes.
Check soup for seasonings. Add more salt, pepper and fresh parsley, to taste.