Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.
This is a scary one isn't it!
I have a number of the non-Pentax infinity focusing Pentax adapters and the first experience was with a bellows that I purposely tightened on hard (to get the bellows and body to orient properly). After the initial sparring to get it off (I finally figured out how) I determined that if you remove the little spring clip, bend it back toward the adapter a bit, and put it back in place, the adapter holds OK to the camera and it does not get stuck on the camera! There is a bit of a knack to adjusting the clip and taking the adapter on and off the body, but once you have the procedure down, (do it at home under calm circumstances first) it works well. Having the little spanner wrench that is supposed to come with the adapter is a BIG help!
I don't know why, but there is something special about some of these older screw on lenses that add to the image. The bokah, the contrast, they really knew how to make lenses then, and this was before computers and CAD software!
Regards,