Narrow down the scope is important for any troubleshooting for a complicated CCTV installation.
Try below test to do a simple test to decide whether pan-tilt itself go problem:
1) connecting only the suitable power to pan-tilt (mostly 24V AC 2A)
2) by adjusting the dip switch to see if certain movement is ok.
3) if there is no problem, the problem on the movement of pan-tilt unit may be parts outside the pan-tilt itself.