Bad transaction from a Facebook seller

I hope you used a credit card to pay for it. If you did you are in the drivers seat. He is responsible for the parts until they are delivered and accepted by you. If he didn't insure, his loss and HE needs to take it up with UPS... NOT YOU!!!

Did you note the damaged box when you signed for the carb box. That's on UPS...

File a claim with paypal. If they balk, go do a chargeback through your credit card company. You may need to ship the carbs back.