[IXLR8]

This is a guess, but I believe the nut labeled 'B' (for Battery) will go to- the fusible link in the schematic then on to the battery, and to the 'B' on the ignition switch. The push on connector below it, this should be the 'F' connection, which is the field, which excites the alternator and controls its output. The 'F' is not labeled on the schematic, it is the lead that goes from the regulator to the single coil in the alternator. In your schematic it is on the left side of the alternator. The 3 coils that are connected together are the actual alternator output coils. From the schematic, it looks like the regulator has a relay that drives the 'Charge Lamp', it looks like there are two relays in the regulator, my guess is the one for the 'CL' is not working if the alternator is indeed putting out. What is the voltage on the battery when the tractor is running above 1500rpm. If the alternator is working, it should be between 14.0-14.5 volts. Anything less then 13.0 and you have a problem somewhere. Keep in mind that the schematic shows the ground wire connections when actually it is the tractor frame, engine block and alternator mounting bracket making the connections, not separate wires.

HTH