I had my distributor cap off the other day and noticed some buildup on end of the rotor (not the middle). It is a few years old but does not have many miles on it.

To prolong its life a bit, can some light sandpaper be used on it and the corresponding areas under the cap?

And I know its best to buy a new one, but this is not a regular distributor so if I can extend its life for awhile by cleaning, thats what I'm after.

put a new 1 on and keep yours in glove box as a spare. i got new ones 5.00

Its for a summit distributor with HEI terminals, if you have that for $5 I'd be on board. The cap and rotor are about $30 from summit.

The tips often get buildup. You can scrape it off with a screwdriver or knife. For a while, the routine was to put a bit of di-electric on the end, it came with the rotor.
Late 70s rotors were shorter by design, made for a stronger spark.
They usually fail under the center, with the spark going thru to the shaft, not tip wear.
You are probably fine, but as mentioned, it is a good idea to get another in the near future and relagate this one to spare status.

I have used a little emory cloth to freshen them up with sucess. Usually when its bad enough to really need it I get a new one on its way if I plan much driving.

post a picture of the rotor or send link to the cap and rotor on Summit....bet i got 1