Starters run the same direction regardless of polarity unless they're the permanent-magnet type that have come into use in the past 20 years or so. It sounds like there's a connection problem, or the battery just isn't up to the task of heavy-load cranking. Do a full-load battery test, where half the cold cranking amp rating is applied for 15 seconds, then the terminal voltage is checked. 12 volt batteries should show at least 9.6 volts at the end of the load test, and 6 volt batteries should show at least 4.5 volts after loading.
Jerry

Last edited by Hotrod Lincoln; 10/22/2010 7:02 PM.
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