Bob,
On the left under Information Resources click on Catalogs and Parts. Under Coleman you will find the 502 diagram. I re-furbished one not to long ago. They are a straight forward design. If you need any help left me know. I you want addition info. look under links at the bottom of the page and goto
http://www.oldtownyucca.com/coleman/
Lots of Coleman information and some harder to find parts are available there.
Chuck