"Theoretically" if you put a different tip top on the rod, you would need to reposition all the other guides and re-wrap them. I really don't know why, in this instance, you couldn't have a local fly fishing shop measure up the remaining tip, and attach a new tip top to it. It's not like you use it for finesse type fishing.
As for replacing the tip top yourself ... if you can get a proper measurement on the tip, you can get the tip top from Hook and Hackle, Mud Hole, Feather Craft, Cabela's, Jann's netcraft or any number of other supply places. You will also need an adhesive to seat it. Again, any one of them would have the right "stuff". Who is it says, "It ain't rocket surgery"? He's right on this one. Simple repair.

And, welcome to the board! I don't think I've seen a post by you before, even though it says this is your third post. You'll like it here!!