As far as I'm aware all drives we purchased were on an OEM basis. The manufacturer will know this from the drive serial number. If you did manage to get an RMA number then you should be aware of the sophistication of the diagnostics they run on their returns.

When we return a batch we often get a refusual for one or two of them, with a report along the lines:

"Stress analysis indicates 15.5G lateral shock indicative of 45cm drop to non-elastic surface with impact at front right edge; platter velocity zero at impact; parked at impact"

That's from memory, but you could the idea. I'd love to see if they can analyse the colour of the shirt you used to wipe the platter, and whether they can accurately determine your fabric softener

Rob