consider you didnt put the wheel in straight (perfectly)
also consider the replacement wheel is generic and of inferior quality.
a very ugly possibility that i wouldnt want to hear..
you opened the televsion and broke the air tight seal, now all the special air is gone.
i would like to think you put the wheel in wrong or the new wheel will change color and get better over time.
have you held the two wheels side by side for comparison?