Pattern Student,
If you do take your engine apart be careful when you pull the cam box off the back of the engine.
You could pull the cams off with it (don't ask me how I know this [sm=spinnyeyes.gif]).
First take the thinner flat plate off the back.
Then you'll see 3 holes...2 on top one on the bottom.
The one on the bottom is the end of the cam drive coming thru from the crank.
The two on top are the cams themselves.
When you start to pull the box off take a small wooden dowel or wooden pencil point and keep pushing those two cam ends back into the box. This will keep them from coming off as you remove it.
Good luck!
JLK