If so, you have two problems. First problem is it's shot, worn out, due to lots of use and now you can see some carbon tracking across the cap. This cap ran a week before the photo, then decided it would not run at all, possibly due to the moisture that got into the cracked areas after sitting for a week at the marina.
Second problem is the wear marks put into the plastic by the screw top on top of the rotor. This cap needed a rubber gasket to avoid the contact and I didn't know it at the time. The rotor quickly ground out it's own path and fortunately didn't break anything in the process.
Here is a thread telling all about it
http://www.network54.com/Forum/424840/message/1212372446
regards,
Paul