A lot of the time you can get a stuck egg out of an eggbound hen with a nice warm bath. You can wash soak her in the tub, a sink, a rubbermaid, a bucket - whatever you've got. Make the water nice and warm (should be very warm not lukewarm but not a shock to put your hand in it), deep enough so it just barely covers her back if she stands (they almost always stand for a bath). Lower her into the water and sit there with her about 15 minutes. She may relax and pass the egg in the bath. You may be able to gently work the egg out with a gloved & lubricated (like KY-jelly) finger. After the bath, put her under a heat lamp to dry & recuperate (if she passed it), or to dry & hopefully relax & pass it.
Once you get that egg out of her, her oviduct may not retract right away. This is called prolapse, and if you catch it right away, you can reverse it most of the time. After the egg has passed, apply some hemorrhoidal cream and gently push the protruding material back into the vent. Put her somewhere warm for a few days to let her rest and so the others won't pick at her. In addition, you may want to put her somewhere dark to slow down the egg development process & give her time to heal up before another egg is ready to lay.
Make sure that your girls have access to a good calcium supplement like oystershell, too. It can prevent egg-binding in many (not all) cases. Good luck!!
