My Graphic View II jumps the teeth in the rail while focusing with the black rea r knob. I have tinkered with all the screw adjustments and have not been able to make it work smoothly. All teeth and gears look ok and undamaged. As some of y ou know, the focus knob runs through the locking knob and they are somehow inter connected. There must be a simple series of adjustment steps that will make the gear at the end of the focusing knob shaft stay securely on the teeth on the und erside of the rail. If no one knows the corrective steps to take, can anyone rec ommend a Graphic View specialist to contact? Thanks.