You're not providing enough information. When you are experiencing the problem and you pull the trigger do you hear a "click" - i.e. internal hammer hitting the firing pin? Or, do you pull the trigger and NOTHING happens - something like this: press trigger......press trigger......press trigger - "boom".
I had a problem with my Mark II similar to the situation I described above. With a round chambered and the internal hammer cocked, I could never predict if/when the hammer would be released when you pressed the trigger. And, it didn't matter how hard you pressed that trigger either. The pattern was something like this:
press trigger...press trigger.....press trigger - "boom" press trigger- "boom" press trigger....press trigger....press trigger....press trigger "boom"
The problem was that the little plunger that sits on top of the trigger (internal) was FILTHY. I had to fully disassemble the fire control parts to get to the trigger and the little plunger/spring that the trigger presses against (I'm doing this from memory - so details might not be exact) That little part was caked with grime, even though the rest of my gun looked spotless. Once I cleaned these parts and reassembled, my Mark II was back to functioning flawlessly again.
The problem with the Mark II, Mark III is that no one ever completely disassembles them to clean the trigger parts. It's bad enough to take these things down to get the bolt out and clean that. By the time you've finished cleaning the bolt and getting to the other parts you can reach, your gun LOOKS clean and now you have to try and get it back together. The problem is there is no way to clean that little plunger that sits on top of the trigger without completely disassembling that part of the gun - I was shocked at what I saw when I did this, and yes, I cursed Ruger for making a 22LR pistol that is so dang hard to clean. Fortunately, you don't have to do this very often.