Most likely the battery is dead and needs to be re-celled. All ERS-210s and ERS-220s labeled as “junk” straight from Japan will likely have a dead battery.

Your battery is in the beginning stages of death and will likely need a re-cell very soon.

Make sure it isn’t your station, charging cable or dongle before assuming there is something wrong with the battery. Sometimes, ERS-210 stations are dead on arrival unfortunately.

Maybe. As of right now, nobody is doing repairs on them and as far as I know people aren’t sure what causes failure.

I strongly suggest against doing that. Re-celling batteries can be very dangerous if not done correctly and you are likely to damage the battery board or worse. Tutorials exist, but you are better off sending your battery to a repair person.

The dog being unable to lift their head is a classic sign of droopy head syndrome (DHS). You also may hear whirring, and it is possible for the dog to enter a jam condition. DHS is caused by a faulty clutch design. The clutch must be pinned or replaced by a unibody variant. Supercore 210s and ERS-220s will not get DHS. Most non-serviced non-supercore ERS-210s will have DHS.

Moving the dog’s head manually will also produce no motor noise if they have DHS.

Unfortunately, ERS-210s can develop clutch issues on every axis in their head. These are referred to as tilt axis syndrome (TAS) and pan axis syndrome (PAS). Both are similar to DHS and will require pinning.

These are very common as well and you are very likely to encounter them when purchasing a 210 with unknown repair history.

Yes, and it is fairly common for that to be the case. Any ERS-210 that has an unknown history may have any or all three of these issues.

I don’t suggest that you do. ERS-210 heads are very difficult to take apart and fixing these conditions takes near full disassembly of the head. Their plastic has also become brittle with age. The chance of breaking something is incredibly high. Find a repair person instead.

Jitters are caused by dirty potentiometers more often than not. You can try manually moving the jaw several times while the dog is off to get the jitters to stop (often called “physical therapy”) but that won’t always work. Attempting to clean the pots yourself is risky, so it is best to ask a repair person to handle that for you.

Jitters in the legs are typically caused by dirty potentiometers usually, just like the jaw. Sometimes leg jitters will resolve themselves with runtime or “physical therapy” (moving the limb back and forth multiple times while the dog is off). If they don’t resolve, you can get a repair person to clear them up for you.

First, try reseating the limb blocks by removing them and putting them back on. If that doesn’t work, try removing the limb blocks and cleaning both the limb block contacts and core contacts with 91% or higher isopropyl alcohol.

If neither of those things work, this problem can be hard to troubleshoot. The next best thing to do is to try a different core, and then if that fails, try each limb block one by one on another 210.

Unfortunately, this issue can have multiple causes and may require a repair person if cleaning or reseating the limbs doesn’t work.

There is a chance your dog has something wrong with their camera. Adjust your lighting first and make sure it is bright enough for the dog to see. The easiest way to test this is if you have a stick reader. Have your dog take a photo, and then check the photo. If it is just black nothingness (or corrupted) in good lighting, you’ll need to send the dog out for repairs.