Polarizing 6V Generators

Only need polarizing if the generator has lost it's residual magnetism. This will be rare. It is said to do it after a rebuild, or extended times of no battery hooked up. Though I have seen them charge right up after sitting for years on the shelf. That being said, when done properly polarizing will not hurt a generator.

Be aware if the generator is am A circuit or B circuit.  This is how the generators output is controlled by the regulator, regulating the field current. 'A' circuit generators are controlled by the regulator varying the ground to the field. In 'B' circuit generators the regulator applies current to the field, which is internally grounded. Keep in mind many generators have been swapped around over the years.

If all else id OK with the generator and it is not charging, polarizing will usually fix the issue

Also note that just as the generator requires residual magnetism to BUILD it's initial generation, mechanical regulators ALSO hold residual magnetism, as a side-effect of their (polarized) DC operation. 

This doesn't mean they won't operate without residual magnetism, they simply develop it, and as such, the residual field augments the active field in regular operation, and thus, adjustment of the regulator is affected by it's augmentation...

OR IF one reverses polarity on a tractor, the residual magnetism will COUNTERACT the regulator's polepieces (cutout and regulate), so the polepiece of the regulator must be exercised and given time to reverse as well, before one can expect the regulator and generator combination to be stable.

So the short story... if you haven't run it in a LONG time, or you've reversed polarity of the tractor, give it some time to settle in, before attempting to 'dial in' the regulator, and expect to have to bring up the throttle and rap the regulator with a screwdriver handle a few times to 'wake it up'.