The lens-cleaning discs with fibers that actually make contact with the lens are bad news. They can easily scratch your lens and make your problems worse. I recommend the compressed-air method. It's tricky not to blow more dust onto the lens than what you started with.
I had been running the same Matshita UJ-815 that came with my 1GHz PB for a year or so without problems and then around the time I moved to NY (early-2004), I found that I couldn't get media that would burn, neither CDs nor DVDs. Before I started having real problems, the comp was still picky about media and would not burn Sony, TDK or Maxell media but after I moved, not a single brand would work. It would show the "failed to calibrate the laser power level" message every time. I temporarily solved my problem when I bought some media when I was back home visiting the Midwest and the discs happened to burn fine in Toast and in iTunes. Then about halfway through the spindle, only one of five discs would burn. I tried the firmware flashes without success.
I was going to take it to Tekserve to see what they could do but then someone told me that I should just buy a new drive and install it myself. So that's what I did. I just installed a new Superdrive (Matshita UJ-85JS/UJ-845-B) the other day and it works like a dream. It was good to get in there and clean the computer too! I am happy that I'm finally able to burn discs again, having been essentially crippled for a very long time. I know this doesn't answer your question but I just wanted to share my laser calibration woes as well. Hope you get this sorted out.