Small Engines (Lawn Mowers, etc.): John Deere lawnmower, john deere self, self propelled lawn mower

Question
Hi Eric, i have a problem changing blade on my John Deere self propelled lawn mower.  190cc   6.75Hp    model JS20  ID GXJS20A133164     i hit a small hidden stump and broke blade, problem is when i changed it i put new blade on but when i try to start it, the blade loosens itself and falls off? i know it is some sort of safety issue, but how do i change the blade? and it will not crank until the blade is installed right, and i have no idea what to do.   Thanks  Ken

Answer
Maintenance sheet link:

http://www.greenpartstore.com/assets/images/maintsheets/JS20_Walk_Behind.pdf

Owner's manual:

http://manuals.deere.com/cceomview/OMGX22621_L6/Output/

1. Lubricate bolt threads lightly with a general purpose grease or oil to prevent rusting and seizing.

2. Install blade so that blade hub (A) fits between blade flanges (B).

3. Install washer (C) and bolt (D). Make sure washer is installed with cup side to the blade.

4. Tighten bolt to 54 N•m (40 lb-ft).


Do you have the JD part number GX22256 washer installed on the bolt?  Is the blade adapter broken?

If you broke the blade there is a chance the flywheel key may have sheared as well.  

Let me know if the links help and if you are using the JD washer.

Eric