My son has had an Early Rider Belter for around 14 months. Recently, I've noticed the free-wheel sounds "gritty", and there is quite a bit of friction if you move the cranks backwards while the rear wheel is spinning, exactly as shown in this YouTube video (posted by someone else... clearly the hub has issues).
I've removed the rear wheel and taken a look at the sprocket. It's not like Shimano hubs I'm familiar with.
Can this hub be serviced? If so, how does it come apart, and what tools will I need?
It appears to have "KENGMIN fastace" printed on it, but a google for this term doesn't provide anything useful.
Here are two pictures of it: