I seriously doubt you will find a used one.
I have a 20 x 10 shed full to the top with old bluesmokes for "spares"
When customers are paying me $ 60 /hr to repair their gear they do not want me to put used parts in there.
There is just no profit to be made from wrecking these engines when you can get Chinese copies for $ 10 ( wholesale price ) or $ 30 retail.
There is 1 to 2 hours work for me to get a crank out of a chainsaw.
There is 10 minutes for me to check a catalogue & I get a new part with 12 months warranty which I can pass on to the owner.
Old used ones could have been sitting out of the saw in a damp shed for 10 years and fall apart or they could have been carefully removed, cleaned, oiled then wrapped for proper storeage.
But the end user has no idea, so will never fir a used crank, unless have pulled it out myself.