Have you tried soaking them with oxyclean? I do just that in my washer.
Cream of tartar; blueing; borax.
I use about 1/3 bottle of hydrogen peroxide when I wash my whites. Buck a bottle at dollar store. Bleach tends to make whites dingy and breaks down the fibers over time. Most oxygen based detergents are peroxide based.
Clorox is always my go-to product for white clothes.
I use a cup of borax in clients dingy whites in the washer. I also use Awesome Oxygen laundry additive from the Dollar Store.