I have heard this about spring "saving" a lot...... Does anyone actually have any experience with a spring that has been weakened like this? Some times things that "just make sense" actually don't
I ask because spring tempered steel is remarkably stable. I have had machines that I know were stored for 80+ years with the foot in the UP position, that once the rust was removed, the spring worked fine. I have had the honor of working hands on with 17th century armor with spring tempered bits that even with a few hundred years of being in one position, still worked flawlessly.
I would be willing to bet that even the most amount of spring weakening you would get over a VERY long time, could be compensated for with an 1/8 of a turn of the presser foot tension..
Now, I should say that machines made in the "modern era" may have a different quality of steel that had some inherent weakness or susceptibilities.
my .02