Shipped a head, then customer says it rattles
Looking for help on how to handle this situation. Never had anything like it before. I had a completely factory glue in 3 wood up for sale, original build. I had played it for a couple months, club had zero issues. Customer wants the head only, no problem. I take it to the local shop and they use an electric heat gun, I watched, to pull the shaft. It definitely was not overheated. They did not clean the head or hosel up after pulling because I was in a hurry to get it to the post office before closing.
Well, my customer builds it up and emails me saying it has a rattle. Neither one of us can send it in for warranty because neither one of us have a receipt of original purchase. I think he or whoever put a shaft in it drilled too deep when cleaning it up maybe? It never rattled in my possession. I don't want to get negative feedback on my profile, and I want to treat the customer fairly.
Looking for reasonable advice and hopefully experience from someone who understands rattles. Thank you in advance. I want to do the customer right, but I also can't afford to be paying for someone else's bad club work. I don't know the solution.