If you google 'repairing' these units, the general consensus is do NOT try dismantling them or rebuilding them ... but what usually happens is that the original factory grease hardens over time, disallowing the pawls to engage with the tiny cog teeth inside the machanism, and often if you flush the thing out well with a good long baslt of WD40, let it sit for a bit, adn then re-lube it with a good quality light-duty spray-lube ... more often than not they can be resurrected back into a perfect working order like that.
good luck ...