For some reason I managed to undertighten the crank bolt on my stoker's left hand crank. On a ride with another stoker it came loose. Although I tightened as soon as he found out about it being loose, it now turns out the inside of this crank is severely damaged

I already found out that Peter White still sells TA Zephyr tandem sets in the correct stoker size, but then I'd have to buy a complete set. Also I searched Ebay and other sites. Would anybody happen to know a place where I could search for a left hand TA Zephyr tandem crank of 172.5 mm?

All suggestions are most welcome!