Sorry for the inconvenience, will try to write in English, Good morning, I am a late learner (71 years old) Parkinson's patient, and am building the GMK6400.. Now I have a pressing question, I now have it for the 27th time complete chassis assembled, all instructions followed flawlessly, and yet again wheels that do not turn, gears that creak and creak and the lock of the weather for the 5th time 2 burned engines. WHAT AM I DOING WRONG ????????????????