This to me is the crux of this issue.
First: At what point in time did you discover the dent?
Second: Did the dent get worse between now and when you purchased the motor?
Third: Who told you the dent was fine and would cause you no problems?
This to me is the crux of this issue.
First: At what point in time did you discover the dent?
Second: Did the dent get worse between now and when you purchased the motor?
Third: Who told you the dent was fine and would cause you no problems?