Ebay purchase issues: Keep or return?

[Softswerve]

Hey guys,

I made a vintage DJ purchase on eBay (I know, I know - none of the sellers here or known dealers had what I was looking for), and though the watch looks great, I’ve run into a few issues that has me debating whether I should return or try to keep - let me know what you guys think:

https://imgur.com/a/CnFvOCx

I noticed the watch was not running after only a few hours of being unworn, so being new to automatics, I took it over to a watchmaker. We realized that the winder had no tension in it at all when turning so essentially it wasn’t being wound. He tinkered around with the winder a bit and got the tension back on it and it’s now winding properly and seemingly working properly, but the watchmaker said this will continue to happen unless I repair the mainspring or get it cleaned/serviced. We also noticed when setting time, it felt very loose compared to how it should feel. He couldn’t tell me much more than that without actually opening it up but because of the authenticity guarantee security tag still on it, he can’t.

It seems like a simple issue, but the seller previously assured me he got it serviced already and that it was in great working order before he sent it off, and this has me questioning whether it actually was or if anything else might pop up. The watchmaker also pointed out to me that the screwheads on the end links were a bit damaged, which again, wouldn’t be a huge deal but because I’m new to this, has me second guessing.

Do you think I should work out something with the seller or just return? Is this is normal for vintage? If I take it to be repaired and we find more things once it’s opened, eBay won’t guarantee a refund anymore because the tag is off but if I send it back without opening the watch, I’d never know. So it’s tricky. Thanks in advance for your thoughts.