On LiteON 20x family I only performed laser cleaning on LH-20A1H (LH-20A1L brother on PATA). I did this because one of my 20A1H had issues with recognizing DVD-R written discs. I did not resolve the issue, but as I remember I was able to make proper Lightscribe discs.
I also made laser cleanup on many other models: Plextor, Yamaha CD-RW, Pioneer, LG ... etc.
If you are not sure how to do this, I would recommend these:
1) Use cotton swabs
2) Use isopropylic alcohol
3) After you have the cotton swab with some alcohol on it's head, just clean the laser smoothly and easy ... in order not to put to many alcohol and also make the proper cleaning. Wait a minute or two after cleaning and then pack the unit.
Hope it helps