Walk Behind Lawn Mowers

I noticed the left drive wheel was not moving. I adjusted the drive cable with negative results.  

I removed the drive wheels and noticed uneven wear to the plastic gear teeth.  The outside of the gear teeth were very worn but the inside of the gear teeth showed no wear.

I then noticed that the wheel adjustment assemblies were bent.  Both of them.  The post that support the wheel was bent in toward the pinion enough to cause the uneven wear.