Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Looks like corrosion in the metal from the pictures. Probably why it had a cheap BIN.

That's what I am thinking looking at the outer rim and may have had the start of cracking in the middle, but looks to have taken a blow in shipping that finished it off. The other wheel shows no signs of fatigue... It was a cheap BIN (but now only worth about that BIN) as the seller did not know what it was and it was left over from an estate sale. Looked on eBay for a spare wheel and the going rate is about $20 (plus $20 shipping from the UK), which is the same as the $40 I paid for the entire thing...