They voluntarily eat tails, but won't touch pinks? That's a new one on me. If you are force feeding them tails, just be as gentle as humanly possible. Nothing makes a snake less want to eat than being force fed, so it's a catch-22. They'll die with nothing after a couple of months, yet they aren't likely to feel much like eating with food being shoved down their throats weekly. I'd offer pinks every day before forcing tails, and hopefully some of them take.