What did you do with the OEM generator? If you still have, I may buy it. Does it have the belt tensioner? All FORD major components were designed to be rebuilt over and over including generator, starter motor, distributor, carb, water pump, and more. Most all stuff made today comes from Cheena and most are just cloned from clones. None are licensed by FORD and nine made like or as good as the originals. Ford Tractors are no exception. Don't assume you have a 3rd Brush. Is there a n HI/LO adjustment screw on the back plate? You would have to inspect it internally to determine if a 3rd Brush even exists, and if so, ignore it, turn it all the way down. Next, the best investment you and your b-i-l can make for you 9N is to get copies of all the ESSENTIAL MANUALS. So, what does the AMMETER show when running? It should have about 5-10 AMPS at idle. Your gen outputs AMPS. Again, does it have a belt tensioner device? If fan belt isn't tight, unit cannot charge the battery. Next is to verify battery is good. Don't assume if you simply charge it to be good. Specific gravity must be met. Have bat tested at a shop under load. Invest in a Battery Tender (Float Charger) for when it is idle. With battery disconnected, verify entire wiring setup is correct via diagrams and your VOM set to CONTINUITY. Do not use a test light -it requires power and you don't want that while testing. Don't use OEM color codes - new wiring harnesses don't ensure colors are OEM unless they are one of the few places that make them all exact-as-original. I suggest you inspect all wiring first (did I mention belt tension?) then once approved, connect battery and perform continuity via cutout. Polarizing the 9N/2N generator with cutout is to arc spark the cutout BAT terminal to the ARM terminal. If problems still persist, you can perform the spark test and begin inspecting the distributor. One step at a time.
FORD TRACTOR 9N-10505-B CUTOUT CIRCUIT TEST:
FORD 9N-10000-C GENERATOR w/ BELT TENISIONING BRACKET:
FORD 9N/2N TRACTOR WIRING DIAGRAMS:
FORD-FERGUSON 9N/2N ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS: