As the tech tip indicates, you have to match the starter with the flywheel teeth. Sounds like someone may have put a 12V starter on a 6V flywheel. Like Bill said above, a 6V starter should work fine on 12V.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.