This sat for a while as I tried with no luck to find another FHF 72 movement for parts, it needed a mainspring. Well last nite I got tired of seeing it sitting there staring at me with those sad puppy dog eyes and decided to try a generic swap.
I have had several stripped down movements for parts from several months ago and ripped apart a barrel from the bin.
took just a few minutes to rewind the new spring onto the original barrel
and sure enough it was a good fit, it was just a bit longer than the original with a different end termination but the arbor did fit well locking into the notch with no slop or slack. It will take about 40 winds which seems like a good average and I am checking for duration to see if it makes 35+ hours like I think it should. Not a direct replacement but it works great keeping excellent time. Note: handwinding a mainspring works best from the out to in.
Can't seem to nail down the year, maybe someone here can.