Trouble arm of hard drive

[Sourcegeek]

Hi, i have some troubles making a lasershow with hard drives..
When i put the two hard drives in the classic stepper motors position, the arm goes down and doesn't moves correctly, the moving is limited =/
So.. How i can fix it? Any ideas?
I just solded the cable to the arm and tried to pull it, but again te moving is limited and doesn't work nice =/

Thanks