I just wanted to post to wrap this up, in case anyone is curious how it turned out.
I'm all set. The seller was aloof at first, I could tell he thought I was trying to scam him. He asked me to send it back on my dime, which I did. (I could've fought that and had ebay compel him to send me a shipping form) He confirmed that indeed it was the exact same lens and that it was indeed hard to zoom. Said it must have slipped past him; said it was hard to check everything. He refunded my money and most of the shipping cost, so I let go the fact that it is indeed quite easy to check zoom action. ;-)
Anyway, I lucked into a good one locally and that's going to be on my N90s probably 80% of the time now. Santa brought me a Nikkor 75-300 f/4.5-5.6 pumper zoom for Christmas, which will be on probably 15% of the time. AI primes the rest.
My Cameras: Yashica Electro 35 GS and CC, Rollei 35, Nikon N90s, FG (2), FE2, and L35AF3, Minolta Freedom II, Olympus OM1N, OM10, Stylus (mju) and OM-D E-M10 III