I have a Zorki 4, when it arrivied it had a ''lazy'' shutter on the slower speeds, 1 to 1/30, mainly. I think, due to lack mof use, by firing the shutter repeatedly the speeds appear fine, also make sure that the take up spool is with the cameras, and that they don't fall out and dissappear, you can make another from a 35mm centre spool, but it ia a hassle, and the take up spools have a habit of getting lost, apart from the above and never change the shutter speeds with out winding on first you should get some good shots with them, Good luck