I removed the faucet assembly from the bathroom sink/basin to replace it with a new one and it’s completely yellowed underneath. It’s not as bad as it was after I tried to clean it with the rubbing compound I would use on my car but still not gone.

I have to get it all cleaned away because the new one is not the same shape at the base as the old one.

Anyone here had experience with this and know the best stuff to use?