I can't find any stepper motors matching that model number in that booklet. There is a list of SST43D motors (rather than STP43D), but there is no 1006 model of those listed either. I did find them listed as 4.7V 0.85A on a Polish web site.
I suggest you measure the resistance of the windings with a multimeter. Also check there is no continuity between pins 1/2/3 and 4/5/6. If the 4.7V 0.85A refers to driving them in unipolar mode, then the full winding resistance will be 2 * (4.7/0.85) ohms = 11 ohms, and they will need about 0.6A @ 7V minimum to drive them at max torque in bipolar mode.
Are you sure that the motors are not mechanically loaded too much, and that you are not trying to drive them to fast? Do they turn if you remove whatever drive belts or gears you have them connected with?
I suggest you measure the resistance of the windings with a multimeter. Also check there is no continuity between pins 1/2/3 and 4/5/6. If the 4.7V 0.85A refers to driving them in unipolar mode, then the full winding resistance will be 2 * (4.7/0.85) ohms = 11 ohms, and they will need about 0.6A @ 7V minimum to drive them at max torque in bipolar mode.
Are you sure that the motors are not mechanically loaded too much, and that you are not trying to drive them to fast? Do they turn if you remove whatever drive belts or gears you have them connected with?