I am a total newbie to cars but am enjoying doing some work on my 1990 Supra. Bought some Powerslot rotors to replace my stock. First, I had the hardest time removing the stock one. Banging the back like crazy until they finally came off. I can't get the new Powerslot rotors to slide on. The bolts come through ok and everything but I can't slide the rotor in. And of course I don't want to force it on. What can I do about this? Is there too much rust on my wheel?