I recently purchased a Fuji 4 stage spray system with a gravity gun. It sprays wonderfully, but I was having problems with the seal on the cup. I called their customer service number twice and I'll tell ya that it was the best service I have received from any company.
They ended up sending me a new cup for the gun and an accessory kit for the cup on their dime. I couldn't be happier with the service or their products.