Dunwoody

I am doing a 25 hour on a Schweizer 300 CBI (I am a pilot not an AME). It has 375 hours and no accidents. I can't get any grease into the tail rotor grease fitting. Its a flat portal that is filled by a needle/tapered adapter. It is blocked and I don't know if the Zerk-type fitting is working. The ball is not at the opening. Has anybody seen this? Any solutions? Does this fitting has a name? Thank you.