How often do 3D printers breakdown?

I have been running my Prusa Mendel 3D printer for almost a year now, and thought it to be a pretty good time to outline the kinds of repairs I have had to perform. Since I built my printer from scratch, the first six months involved lots of trial and error as I worked out the best components. I am going to call that all part of the construction phase and not really part of breakdowns and maintenance. If you are buying one of the awesome RepRap kits that are floating about these days, you are going to avoid most of this pain. Plus if you build an open source printer - you truly own it, and will develop the skills to repair it!

This is a companion discussion topic for the original entry at