Diagnosis
That grinding or clicking sound is almost always the gears in the pan/tilt mechanism getting jammed. It's usually caused by a physical obstruction like a spider web, a bit of debris, or ice if it's cold out.
How to Fix It
Power the camera down completely by unplugging it from its power adapter. Give it a gentle manual pan and tilt by hand to feel for any hard stops. Use a can of compressed air (from a safe distance) to blow out any visible debris from the joints. Let it sit for a minute, then power it back up. It should re-initialize and hopefully move smoothly.
If That Didn't Work
If the noise persists after clearing debris, the internal gearbox might have suffered physical damage from a hard impact or severe weather. In that case, the mechanism itself isn't user-serviceable and you'd be looking at a warranty claim or replacement.
Heads Up
Don't force the camera head manually while it's powered on. You can strip the plastic gears. Always power it off first if you need to check for obstructions.