Mat****a CW-7503 8x SCSI CD burner.

When a blank disc is inserted, the busy LED comes on and the drive makes
odd rattling sounds while it thinks about the disc. It has done this
since new, but originally the busy LED and rattling lasted 10-15
seconds. Over time it has gradually increased to the point the drive now
takes 10-15 minutes (!) to accept a blank disc. I've tried most brands
of media with no change in symptoms. The drive accepts non-blank media
(pressed or burned) within 15 seconds, i.e. the problem is specific to
blank discs. Once it finally accepts the blank (it always does
eventually), there are no issues during the burning process and the
burned discs work just fine.

I opened the drive and found a piece of thin, clear plastic under the
laser head assembly (covering the ribbon cable attachment point) had
warped and was catching on a protrusion moulded into the frame, which
prevented the head from travelling to the outer edge of the disc. I
unscrewed the plastic, turned it over, replaced it, then confirmed the
head was now able to travel smoothly between the bump-stops at either
extreme. While I was there, I cleaned the lens, head rails, and worm
gear with 99% isopropyl alcohol on a Q-tip, and lightly re-lubed the
rails and gear with white lithium grease.

All this made absolutely no difference to the drive's behavior - which
is not surprising since the blank media information is stored on the
inner edge of the disc, whereas the problem I corrected prevented the
laser from reaching the outer edge - so should only have manifested when
reading or writing full discs. The head definitely was, and still is,
able to travel smoothly to the inner bump-stop.

Any and all suggestions appreciated...

TIA

Sunny