Lopi auger making loud thud

[skolden]

My Lopi Foxfire 400 has always made a thud once every now and then by the arm that moves in the back of the stove when it goes up and down but today it really has started doing it quite often. The arm drops quick enough from it's highest point that it makes a thud that is quite noticeable, I was concerned if I might possibly have a bearing going out. There is some old grease that was around that area, is it possible that someone put it in so it doesn't drop quite so easily and prevents the noise? Everything seems to be acting normal other then that, I'm attaching a picture of the area in question. There was also a little rubber piece that I circled that had fallen out just recently that I'm sure is related to this. Seems like the thud has gotten louder through the day so I'm sure something is going to break soon.