Nissan Repair: ignition, center screw, light emitting diode

Question
My 1993 Altima quit yesterday. It turns over fine but wouldn't fire. I took off the #1 plug wire at the cap and left it touching and no spark. I took off the cap and it was in pretty bad shape. Two of the contacts were worn completely down and two were not bad. The spring loaded contact at the top was badly corroded and stuck. It was actually running pretty good until it just stopped. I am surprised after looking at the cap. I then checked the codes on the ECM and got a 1,1 a 2,1 and a 3,4. The last being a knock sensor code. The engine has 460,000 km on it. Is it likely that I have a distributor problem or do you think the knock sensor threw the timing out of whack?
I'm thinking of just putting another cap and rotor on and see what happens. Any suggestions are welcome.

Bruce

Answer
I would think the distributor is bad.  yes, the cap and rotor were worn out.  But, on this distributor there is an oil seal that wears out and lets oil in the optical switch area.  This is the part under the rotor.  You have to take the two screws off and the center screw on the part the rotor goes on to get the cover off.  Once you have done this you will see that there is oil on the optical shutter wheel and the light emitting diode and pickup.  You will probably need to get a rebuilt distributor as I have not seen a rebuild kit for these distributors.