As a lot of you know I have been rebuilding a lot of distributors lately and by far the largest issue with them is this.
to prevent this is really simple most of us old guys know about this, once a year just put a few drops of light oil, or engine oil on the felt pad under the rotor, it lubricates the advance cam and also drives the old oil/dirt slowly out. If it is the first time just lift the pad and see if it is all rusted up, if so unfortunately you have to take it apart and clean it. Hope this helps out.
Points and electronic are the same basically.