You could try youtube.
Test the coils while your at it.
Our factory service manual explains how to test ignition parts with a multimeter,and trouble shoot.
The serial number is important, very important. Just about every Merc outboard and even Mercruisers use what they call Thunderbird ignition. A serial number identifies what troubleshooting methods are used. For example, I have Thunderbird ignition using a magneto and no trigger, so my T/S method may be completely different than yours.
