I own a LHS. If it had been me when we both saw the problem in the store, I wouldn't have sold the plane. I would have been returned to Horizon by me as unsaleable. Or if he still wanted it I would have given him a discount with the "no return" attached.
Here in my store if I sell Horizon and you have a problem I do the talking with them. In most cases they will take my word and ship the part to the customer. Service is all I can offer against the web.
Anything I have here can be opened and looked at. If you find something not right later I will do what I can to make it right. Now just changing your mind is a different issue, then there is a 10% restocking fee if I can resell the item.
I would rather my his business for a long time then just once. Dennis