Thanks so much everyone! Unfortunately, the piece was most definitely broken. On a positive side though, when I took it to a local sew & vac, they saw it immediately and popped out the piece in two seconds. They're sourcing the replacement now (I'm just not in the mood for the runaround, nor to risk breaking something else while trying to fix it!). The piece itself is going to be $25 which I find reasonable. The timing is also VERY off (something I was able to see myself - the hook was a good inch from the needle when the needle was at it's lowest point!) so they're going to go ahead and adjust that and just give her a basic tune-up while they're at it. [FYI: The spool thread was tangling around the hook/shuttle WITH the bobbin case inserted. I took it out just to see what would happen...]
As far as the 'running good' in the listing - I agree that many people will say this if the motor runs and the needle moves, and I would certainly normally take it with a grain of salt, but this was a SEW & VAC company!!! Unbelievable. I'm not worried though as the ebay buyer protection is very clear and strict on these things. The repair shop is going to attest, on the receipt, that the machine was NOT running. It should have been listed as: "as is, for repair or parts" (according to ebay's own policies), so I have no doubt I'll be refunded the cost of the repairs.
And I can't WAIT to have her back - probably next week - to begin sewing with her!
Thanks everyone for the help!