They have a special tool to test each injector....but I think its around 2,000psi....somewere around there.....I guess you could take em all out set them aside.....turn the engine over and see which one sprays the worse....gone be a mess though I would think.
I have a mechanic friend that works at kubota i'll ask him a cheap way or trick to check them for the hell of it. It may be outa time if it smokes alot.
Art