I'm trying to replace the ignition tumbler on a 97 E300. Reason for replacement is that tumbler has become worn and difficult to turn. I've gotten as far as turning tumbler to position 1 and trying to rotate cap with tool 202 589 00 14 00. Unfortunately cap will not rotate the 90 degrees counter-clockwise necessary to release. Apparently, tumbler does not want to release the cap. Any suggestions on how to get this tumbler out?