My '88 300TE started running rough after warming up. It quickly got worse and now does not even start.

I've been reading though the many threads with similar problems. It appears to be an electrical issue (plugs are black and dry). Checked the coil and crank angle sensor resistances and some basic voltages I can measure with a multimeter. Since I had a new cap and rotor, decided to replace those.

After struggling to get the cap off (following someone's suggestion I cut off an allen wrench and used it in a socket to get off the bottom bolt) I found things didn't look too bad but contacts were black and green and looked pretty fried.

To (finally) get to the point, I found there was a black "gasket" behind the cap that was split as shown in the picture. I put gasket in quotes because it is very hard. The question is, what should this gasket look like? Should it be hard and split or do I need a new one? The cap gaskets I've found online are orange. Is that the right one?

Thanks,
BoB

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1988 300TE
1991 Miata