Butterscotch pony makes gallop sound but very loud whirring noise at same time and head doesn't move side to side

First, calling poor Grace at Hasbro will provide fruitless. Hasbro does not make any parts for the full size FurReal Ponies, they have nothing in stock and cannot help you. I, however, can. I am going to post a link to a distressing site that turns the normal FurReal Pony into a fire breathing demon. However, in the process, you can see the diagram of the skeleton of the pony and head. You can search for other links but this is pretty comprehensive. Just don't open when kids are around.

Lisa

http://www.instructables.com/id/Make-a-Fire-Breathing-Animetronic-Pony-from-FurRea/

Hey, do you mean the rubber part? If so you can try gluing it together or replacing the head's skin with a replacement from ebay: Hasbro Fur Real Pony BUTTERSCOTCH Replacement Parts Head Cover Mane Mouth...

Hey, the blue and grey wire under the neck fur does not connect to anywhere. It was likely a debug port while Hasbro was testing the ponies. You can try moving the ear by hand when it's supposed to move but it is likely broken inside the head and would need a lot of work to repair.

Hey, are you sure you are applying enough pressure in the pony's back? It needs to compress fully in order for the 'Riding mode' to activate.

Hey, the sensors are located on both of her hindquarters as you can see on the last page, but don't forget to sit on her first.
https://www.hasbro.com/common/instruct/FurReal_Friends_Butterscotch_Pony_76471.pdf

Hi Where can buy new tail for my daughter Butterscotch pony Furreal Thanks... the first answer is about this repair

The Pony Care Guide refers to an "Assembly Video" on the FurRealFriends.com site. I couldn't find it and even went through a gazillion videos on YouTube. Contact Hasbro directly through this link to see if they can send you a link to the Assembly Video:

http://www.hasbro.com/customer-service/phone-directory.cfm

Yes, that is the fault in question: that plastic cog was supposed to move the head and it's making that noise because it's slipping, because the gear shaft is not properly aligned with the motor - it's how the head mechanism was designed: badly and with low quality parts.
No, this is not automatically fixed by Hasbro with a head replacement - this happens only when the cog breaks due to the abnormal stress that's put on it, not your case. All you can do is to slightly grease the mechanism and refit the head as best as you can.

all things can be fixed,,,at a price? why buy a broken toy? or have i missed some thing out here???
ok im a guy,,but iv missed the point of this,,,maybe thats what you get for being born a man,,
i was born stupid! ....look on e-bay one will turn up one day and i bet that one will work too?

I don't think it is supposed to move at all