I have a 1975 Ducati 860 GT, kick start only model, early production.
There is a lot to not like about the early 860 ignition, the Ducati Electronica system has a very sudden and extreme advance curve that was know to cause early wear of the crank pin. I swapped out the system for a SAsche battery/ coil system, much better. As to the charging I swapped out the original unit from Ricks Moto Electric unit I bought off Bevel Heaven.
To test charging remove the two yellow wires from the Stator to the regulator and using a multimeter on AC voltage attach a meter lead to each of the yellow Stator wires, at 6000 rpm there should be 60 - 70 volts AC. The Stator is a single phase unit on the early bikes.
As long as the AC input to the reg is good then take the red wire off from the reg to fuse box or battery, at 3000 rpm you should have around 14.5 DC volts.
You can check the diodes in the reg/rec by using the diode setting on the multimeter check red to each yellow swapping the neg and positive leads around for each yellow to red, there should be a reading in one direction only.
Another odd thing unique to the 860 early models is the kill switch function, the factory manual talks about the replacement to the electrical module inside the headlight bucket. If I recall correctly if you swap to the Sasche unit this original module is not needed and a simple kill switch grounding a coil will kill the motor.
