hey guys i have a razor pro model and i removed the wheels to spraypaint it once i installed the wheels back in a week or so later the BACK WHEEL had all the flat sides on it, which pretty much turned it into a square... so i bought new wheels and the same problem the BACK WHEEL and i just bought new yaks and the BACK WHEEL has a small flat side and i want to stop it before it has any others... is it the way i installed the back wheel wrong?