Hi there, seems like I have an identical problem on my C210.

I get the message "Camera pan tilt has reached the maximum extent in this direction. Please drag  to another direction"

It's like either the camera gets stuck and wont move like a slipping belt not engaging.

The best I can describe it is if you imagine a clock face and if I set the left limit at say 8 and the right limit at say 4, as i use it after about 5-6 times the left limit will shift to 10 and the right limit will shift to 6. 

Now Im now even getting the full range.

The mark positions arent reliable either.

Its only been in service about 12 days.

A reboot has not fixed the problem.