Geneve Winding Crown/Stem

I have just gotten this Geneve and have a question about the crown - does it look to you like it has been replaced? Do you know which crown/stem goes with this watch? Can I get one and replace it myself, or do I have to send the watch to Omega? I appreciate any help you can give. The picture of the watch is the first attachement and the back of the watch (with the wo numbers) is the second picture. Thanks.