Common Issues

As these pups age, unfortunately their parts do too. While very hardy and durable, the 110/111 may still need a repair in its lifetime.
Do not attempt AIBO repair without knowing what you are doing. These dogs have proprietary parts and are extremely fragile. Even seasoned AIBO veterinarians have had repair failures. We are not liable if your dog breaks.

Lockup
The nylon input gear in the dog's leg will have its teeth shredded by the motor, typically resulting in the leg locking up and becoming immobilized.
This can be remedied by replacing the gear, but this is not a permanent solution and it may be locked up again in the future.
The dog will typically make a loud grinding/growling noise for a moment as most, if not all of the teeth are shred at once. If kept running, the leg will not move where the gear was shred (hip/shoulder will stop the entire leg from moving, elbow/knee will only stop the lower leg).
The leg may not be locked up if it is caught and the dog is powered off before too much damage is done, however when manually rotating the leg it will make a noticeable growl due to the broken teeth caught inside.
If attempting this repair yourself, be sure to clear ALL of the teeth. If any shred teeth are still between the motor teeth, it will immediately shred the new gear before you get any use out of it.

Slip
A whirring in the legs of the dog as it attempts to sit, lay, stand, etc.
The cause is generally not known, though a recelled battery is usually deemed the culprit due to a weight inbalance.
Running a dog with slip will typically only make it worse.
Replacing the leg block with a new one or switching the battery may remedy the issue.

Jitters
A buildup of dust in the dog's potentiometers causes them to send inaccurate readings. This makes the dog try to fix it repeatedly, resulting in the affected part "jittering" or shaking.
Minor jitters can be cleared with runtime and physical therapy (manual movement of the afflicted part), while major jitters may require disassembly to clean the potentiometer directly.
11X pups have very unrefined movements in general! Jitters are noticeably different from typical 11X behavior, usually kicking in once the afflicted part is given power/moved.

Missing ears are common, as they were held on with rubber which has now decayed and melted. This is solely cosmetic, and will not harm your dog. 3D-printable replacements do exist if this bothers you.