Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Sounds like the nipples are damaged to me, try a different grease gun and hold it on tight. I have a spare bolt and would modify it to screw in ones for you on an exchange basis then all you have to do is undo the nut and push one bolt out with the other, OK the nut would be on the other side but you have to be nit picky to pick that up.You need to grease these every 1000 miles MINIMUM as the collar wears more than the bushes and is damned expensive to replace
You won't know until you take it apart.