Two times in the past few days I have had trouble with starting my 87 300E. Tonight was the worst. I put the key in and turn it fully. Everything looks good but the starter does not go. The lights are bright. I turn the key back and forth 5-10 times and wiggle the gearshift to be in P. Finally the starter goes, engages and the car starts right up.

How do I diagnose and fix this? Hopefully I can start it tomorrow to get to a tech sesssion.