I have my tumbler out now. I was using a screwdriver to turn the mechanism to the first position so that I can depress the lock pin to pull the assembly out. But, now I'm not able to turn the mechanism. Probably the same problem that was causing the key to intermittently not turn. Eventually, the key did turn. I suppose I'll have to just keep trying until it mysteriously turns. Then I'll pull the assembly out. Any other suggestions on how to get it to turn???