An old note:
In 1952 the length of the arm was increased slightly longer to activate for a longer period of time. It increased the output by 1/2 psi.
That's all good and fine but many of the old generation pumps were rebuilt multiple times and like carburetors, who knows what parts have been swapped or replaced.
Today we have rebuilt second generation pumps and new clones.
If there is a concern , the pump output can be measured and compared with the specs.
