Either way will work except that the service starter wire has - as I recall - a female spade lug terminal. I did forget to mention that the service starter wire is before the PNP switch so a bad PNP switch would also prevent it from starting even if the starter is good.

Klaus, the screwdriver trick is a good one that has saved my bacon before. For some unknown reason Mercruiser uses a solenoid relay to switch power to the solenoid on the starter on their outdrives. I was about 40 miles down the lake when the solenoid relay died and my boat wouldn't start. The screwdriver tricked worked like a champ and I got us back to the cabin!

...Lee