Hello i have a 60 hp mariner s# a197683 and i am having trouble pin pointing why it is not charging my battery has 12.6 volt when not running and when i start the engine it will slowly drop to 12.2- 12.3 volts i tested the startor for continuity and it seems ok some friends said to check the rectifier, i know were it is located but i am not sure what the reading should be on each of the three pins mabie i am wrong and it is something completely different any help on this would be greatly app.