zack's can repair just about anything
has an house machine shop too.
that said, sometimes old school shutters ( like degroff pistons )
use a dry lubricant ... like graphite dust ...
charlie webb, a pro who used to post here often, used to recommend
lubricating the degroff pistons with graphite dust ...
(i am guessing that old piston shutters might be the same)
i did this same treatment on an old boston pencil sharpener when
the gearing got clunky, worked like a charm ... i realized that the
pencil lead ( graphite ) lubricated every sharpening ...
good luck !
john