I'm assuming that you're just turning this on and nothing is happening, right?
It seems that the most common failure in these units is the rubber belt that opens and closes the drawer (for the disk), has gotten old and loose, so that the drawer doesn't actually open or close.
It's just a glorified rubber band, it's not (usually) hard to get at, and replacements can be found at repair and parts shops.
That said, I've gotten some fairly long usage from a regular rubber band replacement. Just make sure that it doesn't fit too tight (or too loose), just snug.