Thanks for all the advice! I think I will give the retro clean a try and will proceed slowly. I will repurpose the embroidery squares into quilt blocks if the stains won't budge and/or the fabric will be too damaged.
@ManiacQuilter2: It's depends what country you're located in, but I'm looking on Amazon. It looked like I could also get it shipped to store at a Walmart but I haven't looked too closely at that option.