Pentax K2 ASA selector ring.

If the owner of the Pentax K2DMD is reading this... Great!
I have come across this and the way to change the setting is done by gently pressing the black stub intowards the camera and using one of your fingernails to change the ASA setting to a different one. Thats what the serrations are for!. Make sure you have selected nil exposure factor ie X1.
A close glance at the X1 setting reveals a small red dot. Not the lens alignment dot mind you. this is to check to make sure.
Try it and see.