kcrossly, you asked of "Ace, where was your refurbished lens manufactured? Why should you toss the filter?"
You will find that an extremely high percentage of lens are manuafactured in Japan. I in fact of never seen one made elsewhere although I'm told they exist. As to why the filter should be tossed, many people feel it detrimental to add more glass of unknown origin to the front of the lens. It does introduce another surface that may or may not control reflections, flare etc. as well as the front element of the lens. It also can increase what is called vignetting, the dark shadows that occur in the corners of an image. On some lenses, and depending on how they are used (aperture and field of view) basicallly the filter can be in the picture. Since it is so close, it will be fuzzy as it is out of focus.
I suggest you end this thread and get on with the purchase of the lens. 9+ pages is definitely "analysis paralysis". Once you get taking pictures and learning, then introduce a new topic based on the future question.