Change the tumbler AND the steering lock.
Use the search function.
I did the tumbler only but did the steering lock
a few days later cuz it still did not turn again.
I was lucky to get it to turn after
45 minutes of jiggling.
I left the key in the ignition to allow
tumbler removal again.
Do BOTH now and rest assured.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD