I have been cheated by a Chinese (ShangHai) person. I was so trust her when she presented her piano to me, so I paid $100. It was a 2004 Yamaha U1, asking for $5,000, cheap and new!! Good Deal! But I am still uncomfortable as it was not small amount of money. So I hired a tuning technician to check the piano. It has two cracks, one big and one small!!!! The technician works for Yamaha at steels and yonge, he said since this 2004 piano is in apartment, the cause of the crack is dryness and lack of good care! So such thing is not covered under warranty (this piano still has 5.5 years warranty). Plus the warranty is usually covers the piano tuned by Yamaha every year.
So hire a technician if you want to buy 2nd hand piano, it worth the money!!!! 切记!!!!