Crown will not tighten down...
The case tube and crown on a Rolex watch serve several functions. First and foremost, to keep moisture and debris out of the watch. When they wear out, chances are you may need to replace one, or both of them. Replacing the case tube is the more difficult part of this job, but, as you will see in the video below, it is fairly easy.
Click here to see crown repair
Watch the video here!
Where to get parts...
For Rolex watches, getting parts if you are not a dealer is going to be rather difficult. You will most likely end up on Ebay.
However, you can get some parts, aftermarket, from suppliers. Make sure you know exactly which part you are going to need before you order the wrong part, and waste some money.