Missing chess pieces near the Endgame :)

[Red]

Is it possible to gather all the chess pieces one is still missing, when the game is near the ending? I am missing exactly one black and one white pawn. I could even get the white king, after I didn't take it the first time. How is it with pawns? Do I need to re-search everything harder or might I need to restart the whole game if I want that achievement?

I mean. Are all the pawn locations still accessible near the ending? My saves are only either very early or almost at the end of the game :D