Red fading on Color LaserJet 1600

Over the past month we have noticed that the red colour on the left hand side of pages printed by our Color LaserJet 1600 has not been printing very well. I assumed that this was just due to a faulty cartridge that was not feeding toner to the left hand of the page. A replacement toner did not fix the problem so after a bit of Googling it turns out that this is a common fault with the CLJ 1600/2600 series of printers.

It seems that the physical layout of the printer is such that the fan has a tendancy to blow dust onto the laser/mirror housing and the red colour optics are lowest in the image so they collect dust most noticably.

I found a couple of suggestions giving details on the best way to fix this but found a document from Don Thompson to be the most useful. It gives a step by step guide as to how to take the printer apart, clean the optics and put it all back together again. It worked first time for me although I did forget to reconnect one of the cables so my first poweron complained of a fault. Once I had reconnected that then all works fine.