I've had a 48/24/48A drive since the Fall of 2002, in fact it's a "0000" TLA revision. It has worked very well for me. After I bought a premium last summer before the stock dried up, I semi-retired the older drive in a secondary machine.
By your post, I assume you were using the latest firmware, 1.06.
As Heavyload mentioned, have you tested it with multiple brands of CD-RWs?
When you said identical drive, you mean you have another 48/24/48A drive that works fine? If that's the case and they're both using the same firmware, I would check the revision numbers of the two drives, see if they are the same TLA revision.
The TLA number uses the format "XXYY" where XX is the hardware revision and YY is the firmware revision/update. If the models are the same hardware revision, but have different firmware when shipped, then flashing the drives with identical firmware should make the drives literally "identical".
If they have a different hardware revision, it may not really mean anything significant. Usually newer hardware revisions are just refinements in production to make them cheaper to build, etc. However, there is the tiny possibility it may make a difference.
I think that the "0000" original release hardware versions of the 48/24/48A drive had a glitch with the drive getting stuck when opening and closing. I never ran into the problem myself, but I believe I read about it in these forums many moons ago.