Bucky is obviously in distress. Tony can talk all he wants but he's just going to get a wide eyed wild look. He can't be back with them. They'll wipe him again. They'll put him back in the freezer. He only knows basic maintenance on his arm. One mission he had welded a few lines back together and they had flipped out. As far as he'd been concerned, it'd gotten the job done.

Prisoners aren't usually terribly cooperative, Tony.