I have found that they can't use my waterers with the peepers on (heated nipple buckets). I had a mean old bully that I tried them on, she did great with them on till winter came & the nipples came out...
She has been separated 2 weeks with high protein feed for 1 week. It didn't help a bit. Within the first minute she grabbed a feather from the head hen who was not happy with that. But she went on to pluck her sister right after her beating, lol. I don't think there is any reforming her - she's a plucker now.
I had an old red who would do it occasionally, but if I separated her for a couple days she'd stop still someone looked weird or off, then she'd start again.