As I understand it the American Overseas B377s that were passed on to Pan Am also had their original Curtiss electric propeller pitch controls replaced by Hamilton Standard hydraulics.
It seems, reading accounts, that the Curtiss was troublesome in its basic electric operation and gave all sorts of control problems and malfunctions, but was lighter, whereas the Hamilton Standard, using conventional hydraulic technology with all the associated heavy pipework but with the hollow blades to try and minimise the weight, was prone to incidious metal fatigue of the blades (suspected to start with FOD damage), which led to in-flight failure. Eventually HS did a new solid blade. Certainly if you look at how things developed hydraulic controls became universal, as did solid blades.
Some years earlier the Curtiss C46 initially had (of course) Curtiss electric props, which were such a nuisance on "The Hump", and other WW2 early deployments that aircraft with hydraulics were sent out from the USA as replacements. You wouldn't have done this unless there was a serious issue. It was a major part of the C46 getting the nickname "Curtiss Calamity". Quite why it was felt by some (not all) Stratocruiser purchasers that the old problems were solved, only to find in service they had not been, I am not sure.