Thanks again Unclenick. I am pretty certain of the problem. It's not a dirty gun as I keep all my guns clean. It's I took my gun apart the other day and did a "Dry run" of a trigger job. I found step by step instructions on the CZ Gunsmith forum and before I "Did" the job I wanted to be certain I could take it apart and put it back together properly. In the process I am pretty sure I bent the Sear spring a bit. This is why I asked the question of what engages the single action so I could be sure that it was something I messed up and not some other problem.