What kind of needles do you have? I ask because different needles could do this for different reasons. I think I would try actually washing a small part of what is stained to see if it comes out. Since it's acrylic yarn, I think you stand a good chance of it working. I hope so.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper