Now I am almost sorry that I asked this question. (JK) Even so, not sure what I will do about my presser feet .... up or down .... just not sure what to do. I wasn't thinking that the spring would weaken but would maybe become permanently squeezed somewhat (so to speak) more than it normally would be and therefore would not hold the foot down with as much pressure as much at it used to or should. Not so, SteveH? I would have to defer to your expertise as you appear to be the knowledgeable one on metals and old machines. At least you have certainly had a whole lot of experience base on all the info. in your posts about things you do and are into.
Will have to think about this but I am certainly leaning heavily toward leaving the foot up as per several of you experts in vintage machines have said to do. You have worked with, cleaned, and used more old machines that I will ever see so I guess that is the best way to go.