Farmall Cub

Dad's cub still doesn't show a charging condtion despite all efforts. According to Jim Becker, I have wired the tractor correctly. A new wiring harness was used as well as a new ammeter, new voltage regulator, new battery cables, and new battery. The lights work so, I sorta think the switch is ruled out. Also, when the lights are turned on (tractor not running), the ammeter shows a discharge, ruling out the guage. The generator has been tested twice by two seperate rebuilders and tests good. We have scraped paint off the tractor from front to back....I wouldn't think we have a ground problem. What do I check next

I know you said you changed the regulator, but it wouldn't be the first one that was bad out of the box. Have you tried grounding the generator field terminal and checking to see if it is charging?
Check the last 2 diagrams in the link below. They are troubleshooting flowcharts. One is for generator / regulator, the other is generator / cutout.

Just got a phone call from Dad......mysteriously, the generator is now charging. I guess after removing it a couple of times, it has grounded good enogh to show a charge He also said the rebuilder did something to it yesterday...something about the brushes "glazing-over" Anyway, I think I'll go by his house at lunch and check it out. We may have just put the finishing touches on ole' Bingo