[Yashinoff]

The lens stop down with very light pressure on the pin when I had it out of the camera. The diaphram doesn't look oily. However, when the lens is out the pusher plate move quickly and doesn't seem to have a problem.

If you have the camera on you, open the back, set the shutter to B and fire/open the shutter so you can observe the plunger and pin from the inside. I had a problem with an Edixa where the pin was getting stuck between the plunger the bottom of the lens throat, I was able to see it happen by doing this.