This might be one of those silly questions that needs to be asked because this is my first auto paint job.
I'm sanding and preping my Panel truck for primer, when I got it parts of it were already primed, the roof and jams where done and the rest of the body just spot worked. It was done with the correct primer for the paint I'm using also. The question is about the older primer, some of the areas around the jams have been rubbed smooth/shiney. I've checked and there is a good thickness of primer so I'm wondering if I can just lightly sand these areas and put on another light coat of new primer or should I sand it well down and three coat it? The roof has just got a lot of dust on it and I've tried cleaning and sanding some of it and that came out very nice. So its mainly the door jams I'm wondering about.