To Naples: I'd be buying a CD-ROM drive as a replacement. I see the "geeks" deal largely in used items - no thanks. It would be worthwhile to suggest which among the units that the New_Egg outfit sells.
To Mr. Knife: I took one of them apart. I couldn't find anything binding nor any obvious disconnection. The other drive seems to have the lid plastic-welded to the front panel - possibly to meet some liability worry about laser radiation.
To TCS: I searched the Firmware site. There was no hit for one of the type numbers. The only hit for the other type number was a request for info - no answer.
I'll thank you all and be on my way after the suggestion of what brand(s) to buy.
It's just not worth any more of the time time of you gurus.
sc