I have a Grohe faucet in my kitchen that works fine - no leaks or drips. However, the neck of the faucet does not swivel the way it is supposed to. It sticks and is hard to turn. Could there be a washer or something that needs to be replaced or is there some type of grease or lubricant that can be used to free it up?

The O-rings inside the faucet column need lubricant. You have to dismantle the faucet to get to them. Close water, remove pull-out handle, remove house, lift the column shell and lubricate. I would suggest to replace the two O-rings as well.