Basically what's happened is handle would spin but not bite the cogs and just do nothing, i then dismantled it and the cog pictured below fell out.

So if anyone has done this before, what's involved in fitting the electric one, has anyone done it and are all the plugs already there or is there more then meets the eye?
Or as advertised in the wanted section can i just get a new cog to replace it and it'll work good as new?



