I'm afraid that now days a lot of them don't have mechanics that know how to hook them up or test them. I needed my tractor injection pump timed and the dealer had it 6 weeks and it would barely pull itself on the trailer. ran worse than it did when I took it there. To the dealers credit he did not charge me for it. The manager told me that he 5 mechanics on the payroll but only one was a real mechanic.When I bought my first dump trailer it would dump light loads, but failed to raise with any substantial weight in the trailer. The dealer was stumped but eventually figured out that the up and down hoses were reversed on the pump. No they do not always try before we buy.