Printer and Photocopier Troubleshooting and Repair Collection : Cleaning laser printer optical path     
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Cleaning laser printer optical path

As noted below, the optics are delicate and easily damaged. Use an air bulb to first blow off any loose dust/toner. Then use isopropyl alcohol and a cotton swab or lens tissue to GENTLY clean the exposed surfaces. DO NOT disassemble any optics components - the alignment may be critical.

(From: David H. (textool@aol.com).)

It's always a good idea to clean the entire optical path from the laser (diode) forward. Most of this is inside the scanner module and there may also be a long external mirror.

With time these surfaces become coated with a film of toner/dirt and the laser beam reaching the drum gets weaker and diffused. Print quality suffers and later "beam detect" or "scanner failure" errors will occur, which may be intermittent at first, but eventually they will shut the printer down completely.

So open up the scanner module and gently clean all the prisms, mirrors and lenses. I say gently because the mirrors are front coated and the lenses may be plastic which can be scratched by aggressive cleaning with cotton swabs. Clean the external mirror if there is one. There is also a beam detection sensor which will have it's own small lens or prism which must be cleaned. Good luck.

In my experience dirty optics has been the they most common failure in 4+ year old laser printers with Canon engines.