bc, an old indian trick taught to me by an old indian...

Put a pan of water on the stove and get it to boiling. Take your arrow and stick the nock in the water for 30-45 seconds. The hot water makes the plastic pliable, but not so much as to distort it. Take it out, give it a quick shake to get the water out of the nock's throat and then snap it on and off the string a few times. The plastic cools pretty quick, so you might have to repeat that a couple of times to loosen the nock fit up where you want it.

Do your bestto push the nock straight on and pull it straight off while your doing that.If you twist the arrow too much, itcan distort the nock's ears and make it shoot crooked.