How would you handle this request

[mickisjunk]

I sold a vintage 1950's item. In my description I stated I had not used this item.  I also state that due to the nature of antiques and vintage items all items are sold "AS IS " and all sales are final. I do not accept returns or give refunds. If you need more photos or have any questions please notify me prior to making your purchase. 

The buyer now wants to return saying the rubber seal is worn out at it will not work. 

This is my first refund request and I don't want a bad mark on my site. But I also can't guarantee vintage items.  

As a seller how would you handle this matter?