This is a rip off. I have already replaced this part once and I don't intend to replace it again. The plastic gear teeth are stripping away which alters the self -propelled action of the drive wheels.
I have gradual slope in my back yard and it is extremely tough for me to push and turn this mower. The shaft is not bent, but it seems that the left side is worse then the right.
I would expect to receive this part free of charge, unless you can send somebody out here to determine what the problem is.