Troy Bilt Self propelled Walk behind Mower

[jasbo]

This a Model l675 When mowing the left wheel doesn't move as fast as the right wheel causeiing the mower to keep trying to go to the left,i know the gear is worn in the left wheel but i don't think this is the problem.Hope some one has some answers for me.Thank you all
Jasbo

 

[EngineMan]

Is the gear worn in the right wheel has much..?

 

[exotion]

Gear key might have broke. Check the transmission make sure there is ample grease in it.