I think I may be in the same boat. Once in a while when I go to start my 91 500SL none of the dash lights will go on, only the SRS light, and the car will crank but not turn over. If I cycle the key a bunch of times eventually the dash ligths go on and the car starts no problem. It is a very intermittent problem and the dealer said they could not even diagnose it since it did not happen often.
Is this similar to your problem? You think its worth it for me to replace my ignition tumbler and see if that works? I wouldhave to replace my regular key and my boxed key though.
Thanx much, any advice would be much appreciated.
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special