It's just a pressed fit. You can drive the guide off by supporting the bearing and using a punch (brass preferred) to tap the guide by the lip inside the bearing.
If you don't have a press, I'd use a vice to just press the bearing back on or put the new bearing in by laying it flat on a hard surface and using a small board on top of the guide, gently tap it on.
depending how tight the old one is, you may need to heat it up. You can also cheat by putting the guide in the freezer overnight and warming up the bearing a little bit before you assemble them.
absolute worst case, Larry Stock over at Pantera Parts Connection sells them both as a unit. I had to do that as my bearing just slide on and off the guide.
I'm attaching some picture in case that helps.
