Thanks for the info. I've bought quite a few 1.8 inch drives "as-is" from eBay, and my results have been hit or miss. If it was new, it shouldn't have any foam on it - foam means it was pulled from another player (like an iPod, possibly). Check the bottom left corner of the drive label, to confirm that there's no Apple logo on it.
My only suggestion to you is to test the drive outside of the Zune - it's really the only way to ensure that the drive is working. And, if it is working, then it could be another problem (like the circuit board). If you are willing to wait a few weeks, this converter should work on a computer with an internal IDE interface, or an IDE USB external interface:
DealExtreme: $4.89 ZIF to 3.5-inch Bilateral IDE Hard Drive Converter
I'm going on the assumption that you are technical, since you've already opened up your Zune and did surgery on it.