Super 12 charging problem

My 1968 super 12 seems to not be charging the battery very well. I did change batteries, thus have a new one.
How do I start to tell if it is the generator/starter or the voltage regulator, or what?
Thanks

The first thing (and easiest) is to check all the wiring. Bad grounds are the bane of most electrical systems. Make sure all connections are free from corrosion and that grounding points go to bare metal. There is a grounding point on the regulator that sometimes gets gummed up with oil and gunk over the years.

Once everything appears to be connected properly, check the output with a standard old voltmeter. Simply put the red lead to the positive and black lead to the negative. Look at the reading without the engine running. Start the engine and run it up to operating speed. You should see a definite increase in voltage if the system is performing correctly.

There was a way to adjust some of the older Delco/Remy regulators. Others can't be adjusted. If you find that you are in need of a regulator or starter/generator, check e-bay first. The starter/generator can also be rebuilt at a good auto electric shop.

Remember also that the engine will have to be running at mid/high RPM to put out full current. If you continually run your tractor slowly, putting around the yard pulling a trailer or something, the battery may never be getting a full charge. Also, using the headlights at slow RPM also may create a negative charge situation.

Doesn't your tractor have a voltmeter, or light on the dash?

It does have +/- ammeter. It never seems to show +.
Thanks for the ideas

Positive and negative on what, the ammeter?
How do you tell if it is the starter/generator or the voltage regulator that is the problem?