Production should have been driving them down, but they were being kept 'stable'.
This led to the inflationary effect of malinvestment in higher goods, since the distortion of the price system and interest rate led investors to think there was more savings to support capital investment, then there was.
Prices don't have to rise for inflation to accomplish it's destructive work.
Coolidge was emotionally devastated by the sudden death of his young son, John, in 1923. His dead pan concealed a man in anguish. His long hours sleeping, which began a kind of joke in the public mind, show evidence of a deep depression that sapped his energy and probably led him not to seek nomination, although he probably wished to be drafted, and when he was passed over for Hoover, made him feel worse. Then by implication, much of it coming from Hoover’s supporters tried to put the blame for the crash on his shoulders and justify Hoover’s progressive interventionism, which certainly failed. This must have weighed on Coolidge and led to his early death. Considering that his father lived to be a ripe old age. it is not too much to say that he died of a broken heart. At least this is my take.