The CD-R drive in my Cube is behaving erratically -- as in, not recognizing disks and randomly ejecting them.

I would rather not replace it, as I have a sentimental attachment to the money that would require (and I prefer to reduce and reuse old gear, and get it working again whenever possible). The problem does not seem to be a dirty lens, as I have cleaned it with a kit and often the process does not get as far as the reading of the disks before the disk is ejected, anyway. Do these things need lubricated, by any chance?