I replaced the ubis hot end in my printrbot. I've spent so many hours dealing with weird extrusion problems and finally just bit the bullet and dropped the $60 to see if a replacement would help. Print quality skyrocketed. I think I've just damaged the old one over time. The new one heats up much faster and prints much better. Enjoying the whole process again.
I've got a bunch of colors of PLA now too. Exciting!