Put some Blue-kote on the bleeding part to take away the red. Use gloves or it will stain your skin.
I also then sprayed a product called "Bitter Yuck" (find at a pet store) to make the chick taste nasty to the others. Just on the tail end where it's being targeted. I find it works better than Bitter Apple on my dogs. I think it tastes more bitter, maybe. It's sold where dog supplies are in a pet store.
Then I increased the protein in their diet. Are they eating the feathers? Could be a methionine deficiency. That's an amino acid needed to grow feathers. It's found in black oil sunflower seeds but those may be too big for your chicks still. Also it's in egg whites so you can try scrambling or hard boiling some eggs to feed as a treat. I also gave mine Featherglow Eggfood:
http://www.everythingbirdie.com/feeg.html
It's called that because it's made of dried egg white plus other stuff. I put it in a hopper and let them eat it when they wanted it. They loved it. It helps to grow feathers too. I found it in a local pet feed store and also asked another one close by me to stock it. Looks like they market it to people with house birds so it would be with the bird supply stuff.
I did all of this and solved my problem.
