SHUTTER FOR XENOTAR 135MM F3.5

Hi! Got this Xenotar 135mm f3.5 in a barrel.Puzzled with the shutter.Tried Compur 1 from Schneider symmar s- rear element fits like a glove,but the front element is loose.tried copal 1 - that's even bigger gap for front element.maybe it's an odd front element but the whole assembly(barrel) looks ok.
Any thoughts?
Thank You
edward