I have four bricks all of which are putting out voltage. B&C have power at the terminals, A&D don't. I tried resetting and it worked for a short time before crapping out. It doesn't have that many hours. I did buy it new at the time and only have a chance to use it in colder weather so it sits in a finished train room and doesn't get moved so it isn't like I play basketball with it. Do you repair these?
Not to suggest the obvious (you've probably already considered this?), but are you sure it's not just in TMCC Command Control Mode? That's how the 4 outputs behave if you are in command mode and don't alter the voltage with a CAB-1 (or CAB-2 if using Legacy) in addition to changing the handle voltage setting.
A and D start with zero volts until you throttle up, B and C start at full voltage unless you throttle down. (though this is dependent on the handle positions, so if they are off you get nothing, but if all the way up, the output will behave as described)
So if you are just moving the handles manually in this condition, you would see what you describe - no output on A and D (since you did not use the remote to throttle up) and an output on B and C that varies with the handle setting as you are expecting to see (since it starts at "full on" from a TMCC perspective, and adjusting the handles results in a proportional setting of the output voltage).
Though I agree the part about it working temporarily after a reset is confusing if this were the case.
-Dave