I HAVE REPAIRED SEVERAL OF THEASE.
IF THE FAN IS STIFF TO TURN IT IS PROBABLY DUE TO THE BEARING SEIZING.
REMOVE THE FAN (NOT AN EASY TASK) AND DISMANTLE IT YOU WILL NEED TO DRILL OUT THE RIVETS HOLDING THE SUPPORT BRACKET TOGETHER.
CLEAN THE BEARING AND REASEMBEL.
BOB
November 2008