if there is a problem with the sprocket that bolts onto the cam shaft, the cam shaft is more likely than not itself damaged, the cam shaft has to be replaced.
A Serious project. You can do it with the help of the folks on this site, but you would have to be walked through every phase of the project. I would probably say, with your experience, or lack of experience so far... Maybe not try it by yourself.
I don't think there is even a possibility that the gears in the cam shafts, not the sprocket, but the gears themselves could jump out of time... It just isn't made that way.
Hope we all wake up and find out that this is just a bad dream
Take care,
Keith