I had a broody speckeldy that disrupted the laying of the others. I perservered with kicking her out and cooling her chest down (usually by blowing on it as too lazy to set up a sin bin this year!) I also made sure I had a handful of corn so that when she was out of the nest box the corn took her mind off of going back in. It worked with her, others are more stubborn.
redmite would be hanging around in the coop and you might see the birds looking a bit pale in the comb, losing feathers... also you might notice that you itch yourself after being in the coop or putting hands in to clean out get eggs etc.#
does sound liek your broody has annoyed the others into laying elsewhere!