CD burning

I have a Yamaha CRW-F1 that has been a very reliable CD burner until
recently. Now I'm burning about 50 percent coasters. Here are some
observations and questions:



1. It appears to be far more successful at writing CD-RW media than
CD-R media. Note that I'm using the same brand of CD-R media
that has worked well with the Yamaha in the past. In some cases,
I'm using media from the same batch, so I seriously doubt that
the media is the problem.

Q. Do CD-RW media require lower laser power than CD-R media? If so,
then the behavior would be consistent with the laser output being
less than normal.

Q. Is it possible for dust accumulation on the laser lens to be
responsible for the problem? If so, is there an easy way to
get inside the mechanism and clean the lens?



2. Sometimes I'll put a blank CD-R in the drive, allow it to
initialize, and then start the burn, only for the burning
software to immediately generate an error message and eject
the CD. But if I then close the CD burner tray with the exact
same CD-R media in it that just failed, it will initialize and
then allow me to burn the entire CD.

Q. What could cause such inconsistency?



3. It has been suggested that one simply use a DVD burner to write
CDs. I tried that, but the resulting CD didn't play reliably
on as many CD players as a CD-R written on a CD burner.

Q. Does a DVD burner create the same size pits in the recordable
layer for both DVD and CD media? I know that DVD pits are
almost half the size of CD pits. If the DVD burner creates
smaller pits, then that could explain why the resulting CD is
not as widely compatible with CD players.