There are cork rings that seal the cover around the spark plugs. It's a good idea to use an adhesive like 3M trim cement to glue them to the sheet metal cover. Ditto for the perimeter gasket- - - -glue it to the cover to keep it from slipping out of place while you get a few bolts started.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!