quamosa

My rear head restraints don't move forward or backwards as the Digital Operating Manual suggests. I've pushed and pulled incredibly hard and I think I might break them. I have searched high and low on the web and it seems I am the only person in the world with this problem. The dealer said I need to drop it off for service but I don't want to pay a crazy price just to have them tell me to replace them or they just knock them with a hammer. My Merc mechanic also didnt know and I don't want to leave it with him either so I'm posting here. Has anyone run into this issue? I dont know if the restraints are stuck or if my car was retrofitted with headrests that arent adjustable. Is there a trick to adjusting them?