Small Engines (Lawn Mowers, etc.): started cord wont pull, walk behind lawn mower, spark plug wire

Question
I have a walk-behind lawn mower, and I can't get the cord to pull.  It pulls out about 6 to 8 inches, then locks.  That's as far as I can pull.  I have had no trouble before.  How can I fix this?

Answer
BRADD, SOMETHING MAY BE STUCK UNDERNEATH THE MOWER.  CHECK THIS FIRST.  IF NOTHING IS OBVIOUS, THEN PULL THE SPARK PLUG WIRE OFF AND SEE IF YOU CAN TURN THE BLADE BY HAND FROM UNDERNEATH.  MOST LIKELY YOU CAN AND THIS WILL FREE EVERYTHING UP AND ALL WILL BE OKAY.

GEORGE