Now that I've seen ALL Episodes it seem ODD that when the main characters are no longer on the show they just disappear more or less ?

Which ones are you referring to? Chano? Nick?

I'm up to where Fish left for his spin-off. Though Ron Carey and Steve Landesberg are terrific the show is stumbling bad at this point. Fish was so integral to the humor. Also, if the guest actors coming to the 12th are commonplace, bland and miscast it kills the episode. I know there are great episodes ahead from previously watching them but I just wish they'd get here quicker.