Dont want to mess up your free camera -tensioning from bottom is how it should be done- but if its like the zorki shutters at all and you can reach the rollers inside lens mount
I cock shutter
then roll the foremost roller
then trip release keeping presure on roller
and then let go

I do it for some reason at 1/20 -slow speeds

Worked on two zorkis out of two zorkis

this when the curtain hangs stopping midway through the frame