One of the issues with the laser cutter is that most modes of failure have the same result. If the power supply fails, the magnet sensor fails, the water pump fails, the tube arcs to the case the laser simply stops cutting. It's then a process of elimination to discover what the problem is but it's not always obvious.
Last week my tube started dying, it was a bit sudden since the last tube but if failed in a very obvious and distinct way so I thought it was worth documenting. On all of these cuts you can see that the laser started the cut perfectly but by the time it gets to the other end of the item it barely managed to mark the surface. So now if you ever see this happening on your own machine you'll know that the tube is on it's way out.