Dave, bust going up a rather large hill.
The crank had bust and been welded in the 1930's, we believe after a full astern + steam incident with a child. This broke the crank, a trunk guide and a cab upright (2 1/2 square ash) at least.
No other damage the second time. Though the engine did start to run backwards down the hill, got enough momentum to go over a chock. But it jackknifed the trailer and put a stop to things very quickly.
About a month earlier father experienced a very large noise like something breaking whilst driving down the road, but despite spending half an hour