^ yes you can. Even those hammer dings.
you will leave marks from the roller dies but you will get it straight. On your EW use flattest dies and very little pressure.
I have shown to my customer that you can hit a piece with ball headed hammer and get it fix using EW and shrinking disc.
But I havent seen or heard that you can fix warped piece with EW by wheeling next to bead... Have to try one day.
Prestreching should be done with narrow or curve die and some pressure on as narrow area as you gonna run the bead. You should not go out side of that area.
Lazze has great clips about that:
part 1:
https://www.youtube.com/watch?v=3XBxVtocDqc
part 2:
https://www.youtube.com/watch?v=mTjPZ9ljZ10