I moved last year, which is why I've been only just barely lurking here. I went from a tiny but barely functional shop at the old place to no shop space at all and a garage packed to the gills with crap. All of my keyboards and parts, with the exception of my Filco and an SSK at work, were put into storage.
I just got my new shop space up and running a couple of weeks ago and can now park a car in my garage. I've been slowly bringing my keyboard stuff out of hiding. In fact, I happened upon the jig that used for this the other day. i also found the stash of springs that I was testing. My keyboard enthusiasm hasn't completely recovered yet, but it was nice to type on a model F again the other day.
Regarding model F/M springs, so I haven't really considered that. I imagine that there are differences. I was mainly trying to put to rest some of the debate about these various springs and how they relate to Korean springs.