I agree, refund and take it back. You were right to offer the repair, and that was great. Depending on the person buying the tank, sometimes the buyer get a bad taste in their mouth when something has to be sent back and repaired right away. They will always have an issue with it, (mostly in their head) a squeek, a wobble , a weird noise, all stuff that wouldn't have been there if it wasn't broke in the beginning. I have delt with many of those people in my repair business. I have learned to be the better person and just make it right, even if it cost me time and money. Then I know I did the right thing and I can sleep at night. They have to deal with their own conscience. It also helps your reputation, not that it needs helping, just as long as buyers don't start abusing you, buying it, not liking it,, or made a bad deceision on their part and knowing they can send it back, you don't want that either. I also stop doing business with the ones that take advantage or abuse me. Customer service is tough now days, customers don't take responsibility for their action anymore, they want to blame it on someone else. The problem here is, its not your fault and its not the buyers fault, it the shipping company. They should be punched in the nose by Crius,lol. Good luck