I try and disclose as much as possible with pin buying and selling but the key is reputation. I like to see other past buyers get on a sellers thread and share their experiences. Your reputation is everything in this community. That being said I am a firm believer in once it leaves your house then it is your issue to repair or fix. I sold a laser war for a friend who was moving across the county to a guy who lived about 45 minutes from me and he got about 2 months out of the pin with no issues. Something happened and he didn't know what to do being a first time pin owner. I went to his house and drug one of friends along twice to help him try and fix his issues. We were not able to figure it out so I contacted a pinball repair guy who responded and fixed the issue for a fee. I had no ownership in this machine except helping a friend sell a pin but I was more than willing to make a few trips to use my knowledge to help the buyer out. I had a Star Wars machine I sold to a guy who lives about 45 minutes from me and he had an issue later that I responded out to his house and helped him solve his repair as well. Reputation is everything and you want to make people happy and make relationships that will last. If someone is calling me every day complaining about this and complaining about that then I would probably not do much to help out because they should of inspected the machine or asked more questions before the purchase. I can usually tell the problem buyers when they come over and start pointing out every single imperfection and asking you to drop your price a grand. I just tell those people thanks for coming to take a look but I think I will wait for other potential buyers.