In all the years, since the DT 540 introduction used on tandems, I have not seen a ratchet look like this. It makes me think the metal on the one side is extra brittle for whatever reason so I don't believe it to be a strength or design issue. Does there appear to be any corrosion involved? The common form of failure is from lack of maintenance, the grease hardening up and being contaminated lessening full engagement. And once they slip, that is usually the end of the story, or at least any forward movement. I did hear of one that cleaned up and would engage again but generally the teeth are rounded off from that first slip and the star ratchet assembly is toast. We rode our Co-Motion quad
https://www.precisiontandems.com/qua...nd_of_ride.jpg with this hub on many week long state crossing tours and tandem rallies while always having a spare ratchet kit on board, which includes both pieces and springs. We never needed the kit but would service the ratchet yearly. It is a good strong design evident by the load and stress on the hub seen from the link. It is good to have their special lightweight grease, too. I only know of one ratchet assembly that fits the DT 540, the factory original design that is kept in inventory here, so am unable to confirm whether other models are compatible. I recommend replacing it with the stock ratchet design as you will likely never see another one chip out again.