Still Having Problems
Thanks for all of the suggestions. I am now fairly proficient in disassembling and reassembling the Mark III. The receiver is still so tight on the grip frame that I have to strike it with a rubber mallet multiple times to get it on and off. When assembled, the bolt appears to be functioning correctly. However, I still have my problem with the gun not cocking properly. The hammer does not lock at all.
I used the link that Billy 45 provided and found a useful tip. It suggested that you should insert the mainspring housing in the grip assembly without the receiver attached so that you can see what is going on. I did this and after closing the spring, I was able to see that the hammer strut is seating properly and the spring is providing tension to the hammer. However, the hammer disconnect is not engaging at all when I push back the hammer with my finger. Of course, I am making the assumption that it should.
I'm concerned that maybe something slipped or was bent in the trigger/hammer assembly in my initial attempts to disassemble and reassemble the pistol... grrrr. Nothing looks unusual, but I have no idea what I am looking at.
I've owned a number of firearms including a Ruger AC556 and I've never had this kind of problem.
Any additional suggestions that you have would be helpful.