Bumper replacement for a Jerry 'R' Rauenzahn cue

[ny9baller]

I have an old Jerry R cue and the rubber bumper is missing/fell off. I am wondering how i can replace it and what to buy. There seems to be a thread in there for maybe a weight bolt or screw? I can't really tell. I tried my best to get a good photo.

Any ideas?

 

[chuckpilegis]

I see in one pic buttcap is broke