If you can't refund the refund, use Paypal's Send Money service. Mention the original eBay transaction number in the text box for his bookkeeping.
And if you can leave feedback, do so, without mentioning the refund part. That tends to leave sellers open to scammers.
If you can't leave feedback, you can add a Response to either your own or his feedback if that has been posted. This doesn't affect his feedback score, but it does improve his reputation to those few who read feedback.
"Arrived late but just as described ' would be one suggestion for either FB or Response.