I have a Poulan Pro 31cc. If yours is the same you will need a combination of Allen wrenches, star bit screw drivers, and other wrenches to disassemble the unit. Disconnect the spark plug wire (I removed the wire boot so it would be easier to get the motor housing off). Start from the front of the unit and remove bolts from the trigger housing (4 against the motor and 3 by the trigger). Once you disconnect the electrical connection and trottle cable you'll be able to detached the motor from the gear drive. Focusing only on the motor, remove the bolt in the middle of the drive shaft (it's a small star bit) and take off what I would call the key cover. This will give you access to the locking key. Undo the spring and remove the two side pieces. You will notice on the key which direction to turn it to remove it (I got it by using some vise grips on the shaft and a cresent wrench on the key). Remove the key and washer plate. Take the motor housing off by removing the 4 star bolts holding it to the motor. The motor housing should come right off. You will notice the wheel for the pull cord is inside the housing. Remove the bolts from the plate inside the housing and the wheel should come right out. Replace the pull cord and put your weedeater back together. God bless.
Clayton Paslay
May 2006