My parrot bites his feathers off at the skin he doesnt pluck them out?

the shafts of his feathers seem to be really hard unlike my other parrots which are soft and i can sqash them when we have our preening sessions, he is a Grey and ive had him for 2 wks, hes in his 30s so ive been told by his previous owner who had him for 10yrs, he twitches and flaps his wings like somthing is annoying him, but his skin isnt sore or dry, i mist him everyday, he just seems uncomfortable and i want to help him, ive been a parrot owner for 10yrs but none of my other birds have had a problem, could he have a skin problem or a diet problem or could this now be a pshycological problem as he has been left his a cage for 3 yrs by his last owner, hes very friendly now loves to come out for cuddles and playtime, please help! x