I get so steamed at the idea of people who will exaggerate the condition of items they are selling, then will happily try to resolve a justified dispute by defrauding the shipper and claiming shipping damage.
I also get irritated by iffy sellers whose argument is "but you got a good deal" when it sold at a fair market price with certain condition promised.
I think you did fine with this, and you'll never look back to these "birth pains."
Before you send it to Questar, consider whether you can largely resolve any concerns that impact the enjoyment and performance.
The Barlow lever is almost certainly a matter of adjusting and tightening a set screw. Or an adjustment of the boss hidden inside the lever knob needs to have its set screw loosened, and advanced slightly on the threaded shaft to increase the Barlow friction.
Cleaning of anything can be done with varying degrees of effort required. Feel free to share images or descriptions of what you see in case there are any easy cleaning tricks that might apply.
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In general, Ebay is an excellent source in my opinion - I've acquired ten Questars on Ebay in the last two years (not just telescopes, but each with a mirror and corrector), and have been happy with every purchase, including the one best-condition Questar I have ever seen. Rarely is it necessary to negotiate an adjustment due to a real error or omission in the description - one had undisclosed coating failure on a BB, which would be fatal except for unusual collectability of the item.
I've also had good experiences on CN, AM, and Craigslist, but with rare exceptions even there - and no built-in back-up for refunds like Ebay, which I suggest may be the least "risky" buying venue if one reads the auctions carefully and knows the policies. As it happens, one CN purchase had a documented (not so) "recent" factory service but turned out to be the only one I ever sent in for a factory drive service.
I should probably keep mum and let others see Ebay as risky - to keep their bids away. For example, although I decided against it, that recent Q7 Astro in Newfoundland on EBay was offered for ~$2400 opening bid, and nobody bid. The poor photos suggested possible coating failure, but the auction promised only "needs cleaning" plus the usual Ebay fully functional guarantee. Good deal if only cleaning is needed, bad deal if recoating is needed. Simple solution is to trust the seller, take delivery, then if cleaning isn't adequate ship optics to Cumberland for coating, get an opinion letter to use to resolve the Ebay claim and let the coating work be paid from the purchase price. Which is something like buying a house that comes with a lawsuit. I had been tempted until I realized that I would not easily be able to add the prism and control box from my now-spare barrel to upgrade it.
I will add that no one wants to be "that guy" who will find fault with anything and seek a price reduction. These are used scopes and some imperfections are expected. Only major issues like undisclosed coating failure, failed slow motion drives needing service, and major undisclosed cosmetic damage justify adjustments.
Finally, I'm open to the notion that there may be design improvements that newer scopes enjoy, but I haven't seen any evidence. The acknowledged design improvements were switching optics suppliers in the 50s, widening the field at the axial port in 1964, and adopting Brandon eyepieces in 1972. All the changes since then to my recollection have been mechanical or cosmetic, and typically ones that reduce manufacturing cost (and reduce value in my opinion - I wouldn't say "they don't make 'em like they used to" - I'd say "they can't make 'em like they used to"). Nor have I seen any "environmental degradation" or "wear and tear" that wasn't readily apparent in a sale listing or readily corrected with a routine drive service. I grant that coatings could hypothetically degrade in performance over time, but aside from visible degradation that's easy to disclose and detect, and I have personally seen no evidence of any degradation in a good number of scopes that are 30-50 years old.
The comparison between classic cars and modern cars is an interesting one, because it is so inapplicable. Motor vehicle technology has vastly advanced, while telescope technology hasn't (aside from navigation aids). Someone with no expertise in motor vehicle technology can easily tell the performance differences between a valuable old classic and a modern machine, while even a top expert in optics and astronomical observation would be hard pressed to reliably distinguish between the operational performance of a modern Questar and a 40-year-old model.
