ignition switch difficult to turn to on-crank/would this effect transmission 2 on 2003 Mercedes-Benz SLK320

The key goes in o/k very difficult to turn. wiggling wheel will eventually work but getting worse. then with engine running then the transmission, S/W in S .. pull to drive and it stays in 1st gear as you drive. Need a "How to" to replace ignition switch... are the chances good that this will cure the tranny problem?

Asked by for the 2003 Mercedes-Benz SLK320