I sold a Rogue RP-5 preamp that was less than 2 years old to someone here. About 5-6 months later, he messages me saying there is a problem with it and wanted a refund, lol. I reminded him I am not a store and the answer was no. My recommendation, don’t buy used from a private party and think the private party is going to give you service or a cash refund. Jeez.
I sold a pair o Odyssey Kismet floorstanding speakers to a guy on Audio Circle for a song. I wanted to keep the speakers but I promised my wife I would thin the herd. A few months later, the person wanted me to buy them back from him because he had buyers remorse (he told me so), really?.