I've just finished building a HK 450 GT.
What was up with the 450 TT pros?
Screw heads made of cheese, knackered main shaft bearings, 1 had a warped rotor head, the other a warped main shaft. Both had totally unbalanced blades, the ball end connector threads were sheared on various parts, the main gear was warped on both and the main gear bearing was completely shot on one, a magnet came unstuck on the Turnigy Propdrive motor I ordered with the kit and the grub screw for the motor gear rounded off when I so much as wafted a quality hex driver near it.