Custom, thanks for posting the photo, it's a very helpful reference I would think for Kory. Kory, that is the large rubber piece that I have to fill the large hole if you want to do it correctly. The round hole looks like a pretty typical hole plug you should be able to find at any hardware store in the miscellaneous hardware section such as Ace (in those pull out boxes), Lowe's Hardware (drawer's), etc.
Hope this helps. Still would like to see what the cylinder piece is you're talking about if'n you send me an e-mail with a photo.
Mike