I'm afraid I don't have any experience with a plucker either. Alfie over-preens himself sometimes so the paler feathers underneath his wings usually look a little tatty. But thankfully he's never developed into a plucker. I only know what I've read and learned from others.
It can be a hard thing to break and can start/be caused by a number of things. Illness, boredom, stress, nutrition. You might find that with the new home and good food/lots of attention etc that she starts to improve and lets her feathers grow back in. But it can also take a minor event to send her right back to the plucking habit. A night fright, something spooking her during the day, changes in the household etc. I know it can be really frustrating to watch them start plucking again- especially after a period of improvement. It's important not to let your bird pick up on your disappointment or frustration if they pluck, as this can easily exacerbate the situation. Greys are very empathetic and can pick up on how you're feeling.
Preening and shredding toys may help. And foraging toys too. Keeping her mind busy might help if the plucking isn't illness related. Greys in the wild spend hours foraging for food whereas when they live with us they get it served up on a silver platter (well... near enough!). So if you know what some of her favourite treats are, you could hide some in pieces of paper so she has to work for them. You can get foraging toys too which she has to work out how to open to get the treat. I have a wooden box filled with crinkly paper and lots of different foots toys that Alfie likes to dig around in. I sometimes put a piece of walnut in there for him to find when he's throwing all the toys around.