HELP! - Ignition Problems On A 123

Yesterday, I tried to replace the ignition tumbler on a 1985 300D. Prior to doing so, I read the numerous postings here about such a task. I was able to get the black metal collar off which enabled me to get the ignition tumbler out. The problem is installing the new tumbler. Without the collar, the new tumbler aligns perfectly in position 1, the detente button pops up and locks itself. The key rotates to all positions (0,1,2). I can't get the collar to screw on with the tumbler. With the tumbler and key in position 1, (and the small wire protruding), the collar screwed on easily. After it screwed on fully, I removed the wire which allowed the detente button to click into place on the collar. At that point, I could NOT turn the brand new ignition key (in the new tumbler) left nor right, in nor out. The key was stuck in position 1. It took me 20 minutes of inserting that wire in position 1 to free it enough to unscrew that collar. Why isn't this working?