This article is from the CD-Recordable FAQ, by Andy McFadden (email@example.com) with numerous contributions by others.
In general, you shouldn't. Generally speaking, the only reason you'd need
to clean a recorder or (for that matter) a CD-ROM drive is if you went and
stuck your finger on the lens. Cleaning kits and well-intentioned Q-tips
are unnecessary and potentially dangerous. If you push too hard on the
lens while cleaning and damage the mounting, it will no longer matter how
clean it is.
Some people report drives coming back to life after a careful cleaning,
so there may be some value in doing so. If your drive has become
increasingly flaky over time, cleaning it may help.
[ Personal note: I've never had to clean a lens in *any* CD player,
including a flip-up top-loading boom box that I've had since mid-1990.
I can *see* the dust inside, and I can see the lens, but it has no problem
playing discs. I can't imagine how a recorder that's only a year or two
old is going to collect enough dust to fail, unless you play a lot of
really crusty discs. ]
If you have an overwhelming desire to clear loose dust out of your recorder,
and can't or don't want to send it to a service center, use gentle(!)
bursts of compressed air (like that used to clean camera lenses). The idea
is to knock any dust loose without knocking the lens free of its mounting.
A more vigorous approach is to use a Q-tip and 99% isopropyl alcohol
(a/k/a isopropanol or IPA), but this should only be used if the previous
approach fails. If you can only find 70% "rubbing alcohol", try to find
99% methyl alcohol (a/k/a methyl-hydrate or methanol), which is widely
recommended for cleaning magnetic tape heads. It can usually be found in
paint or automotive stores as shellac thinner or windshield antifreeze.
The Repair FAQ at http://www.repairfaq.org/ has a section about CD-ROM
drives that seems relevant. Find the "Compact Disc Players and CDROM Drives"
section, and skip down to part 4. One relevant quote, from section 4.3,
regarding "cleaning discs":
"I generally don't consider CD lens cleaning discs to be of much value
for preventive maintenance since they may just move the crud around.
However, for pure non-greasy dust (no tobacco smoke and no cooking
grease), they probably do not hurt and may do a good enough job to put
off a proper cleaning for a while longer. However, since there are
absolutely no sorts of standards for these things, it is possible for a
really poorly designed cleaning disc to damage the lens. In addition,
if it doesn't look like a CD to the optical pickup or disc-in sensor,
the lens cleaning disc may not even spin. So, the drawer closes, the
drawer opens, and NOTHING has been accomplished!"