You will not find one. You need to take the back off around the plug to make it fit.

I have a used trimmer with a bad motor. The blade has lots of mileage left. If you're interested contact me link removed.

I would first check the condition of the blades. Look for bent or damaged cutters on the blades that would cause the blades to bind. Try spraying the blades with a penetrating oil like WD40 to see if that will free them. If you still have no luck then you will need to open the tool up and check the condition of the gears. They may be stripped.

That is what I would try. Good luck!

-Mark

First, is the motor turning or not, if the answer is yes, the main gear may be worn out at his center point where a small shaft hold it. When this happens, the main gear becomes off center and the motor gear system is just away from the main gear, in other words, they don't come in contact, so the motor just spin freely. Easy to check, just remove the handle by removing the screws, the gard one screw at the blade section,, remove the 4 bolts that hold the blade system, you will see the gears at this point, and if they are away from each others, you will be able to move the main gear side to side if it is the case. just turn the unit upside down, and the main gear will fall in your hand. Check it out.