IB generator diagnosis update

I disassembled and replaced the brushes, bushing bearing, & end cap because 3^rd brush post was bent. I coated the wire from the field coil where it had been rubbing on the commutator.

Reassembled the generator and fired up the tractor.  At half-throttle the amp meter went all the way over to full charge of 20 amps.  Moving the 3^rd brush didn’t make any difference.  Thought perhaps it was the amp gauge so I opened the switch box.  I removed the old gauge but discovered that the new gauge I had would not fit in the switch box cover so I reassembled with the old gauge. While attempting to close the switch box the box rubbed through a wire in the harness and shorted out resulting in sparks and smoke. I disconnected the battery, taped up the wire, and reassembled the box.  I restarted the tractor and the amp gauge showed 20 amps discharge and the cutout didn’t close.

I removed the generator and disassembled.  Tested the system with a multimeter set at 200 ohms.  I then reassembled and tested again. Results:

3^rd brush and F terminal – Disassembled 2.2-2.3 ohms Assembled – Same

F terminal to ground (case) – Disassembled – Open Loop (OL)  Assembled 3.3 ohms

3^rd brush to ground (case) – Assembled - 0 .3 ohms

Main brush (not the grnd) to ground (case) – 0.3 ohms

“A” terminal to ground (case) – 0.3 ohms

 There is no evidence of any damage or deterioration in the circuitry within the generator or the wiring harness other than at the entry to the switch box where I taped it up.   There is continuity in the wire from the 3-way “S” terminal to the headlights and taillight.  There is also continuity in the wire from the generator Field terminal to the 3-way and in the wire from the “B” terminal on the cutout to the (-) side of the amp gauge. The fuse is good. The resistor reads 3.3 ohms. The switch box has a clean, bright connection to the steering post. Battery reads 6.3 volts.

I opened the switch box and removed the tape from the wiring harness.  The shorted wire is the one that connects the cutout battery terminal to the amp gauge (-).  This might explain why both the cutout quit working and the gauge shows discharge after the short.  ???

Finally, with the switch box still open I ran a jumper from the base of the 3-way switch to the bolt that attaches the box to the steering post.   With 3-way switch all the way in and one probe on the end of the “F” terminal wire and the other on the battery + post I got 3.8 ohms.  With the switch both halfway and all the way out I got 0.1 ohms.

If anyone sees something that could cause the problem please let me know. 

I’m on my way to a electrical repair shop to get a new cutout and have the generator bench tested. 

As for the cutout, I know a regulator is a better option and use them on my work tractors but I want to restore the IB to as original as possible.  She's going to be a trailer queen.