My trailing coil for the back rotor ("T2"), this is an N/A '86, shorts out at the coil. I can see and hear the spark jump through the wire and short on the thing that both coils mount onto. I pulled off the plug wire on coil end, and it was rusty, and I looked into the coil and it was in worse shape that the other "T1" coil. I can't say that I saw rust in the coil or not.

Can I try to scrape off rust on wire, like corrosion off a battery terminal?

Is it bad to try to scrape the inside of the coil?

Is the coil shot, and I need to buy a new one?

Is it even that big of a deal since the trailing coils are more for emissions than
performance, (or so that's how i understand it)?

 

You can clean the contact surfaces, no problem. Inspect the wire boot and the coil tower for cracks. That may account for the spark leakage. If that is the case. replace.

 

Get some new sparkplug wires. That's where the problem is. They're shot.