Eventual success

The new wire from Brillman arrived so I made and installed the new wiring harness.  It looks a lot better and much cleaner without all the electrical tape and cut wires that had been on there.  Its hard to see but here's a pic of the harness connecting to the ammeter box.  The wires are inside the black loom.

The parts to rebuild the generator from Steiner Tractor Parts also arrived.  Included in the kit were new brushes, a new bearing and a new bushing.  Replacing the parts was pretty straight forward and to clean up the part of the armature that the brushes contact was done with some 600 grit paper.  Then I cleaned up the outside and painted it.  After re-installing it on the tractor I tested it by directly connecting it to the battery.  To my pleasant surprise it spun (like a DC motor) which indicates it works.

Thinking all was well I reattached the cutout relay on top of the generator and connected all the wires.  I polarized it by touching a wire momentarily between the BAT and GEN terminals.  Then started up the tractor and basically got no reading from the ammeter - crap, not charging.  Did a number of tests and determined the cutout relay (which keeps the battery from draining and regulates charging) wasn't working properly.  Unfortunately no one sells this type of cutout relay.  After studying how the relay works it dawned on me that it needs to be grounded and that's done by touching the generator.  Hmmm, that new paint could be the problem.  Posted the question to the forum on YTMAG.com and got several responses confirming my suspicion.  So I took off the generator and scraped and sanded the part where the cutout relay and the generator touch.  Put back together, fired it up and ta da, it worked.  At high RPM it charges at about 4-5 amps.  So as it turns out it was a good thing no one sells this cutout relay or I would have bought one and still had the problem.

Here's a pic of the rebuilt and repainted generator.  The cutout relay is the box on top.