@Coffinmaker
Thanks, I just saw the reply over at "clones". I think, together we are getting at the root of the problem. The bolt spring pushing the bolt up may have been carelessly re-installed. As you can see on the photograph, the trigger-guard-spur, that you find on the Russian models, is missing. Its missing because I removed it so the gun would fit in my holsters - for one thing - and because I don't really use it to rest my middle finger on. To do this, after removing the entire lock-work, I had to remove the trigger guard unit, which has a small curved leaf-spring installed on the top surface. This spring applies a little pressure to push the bolt upwards and is hidden from view when the trigger guard is installed back into the frame. I may have "insulted" this delicate spring a bit when grinding off the spur and/or reinstalling the unit after case-hardening again. When I let the hammer down it pushes the bolt far enough into the slots on the cylinder, locking it. However, just a little wiggle will free the Cylinder and it can be moved.
The problem does not really interfere with the guns operation, I found out at the range yesterday. Anyway, looks like I have to open her up again and see if I can adjust or bend this spring a little. I just dread disassembling again, as the lockwork is a bit complicated.