On Classics, the cklist says: BUS TRANSFER SWITCH.... OFF THEN AUTO.
The transfer bus is a large piece of metal, difficult for it to break...
Most probably the transfer relay has got a problem, and that's why the Transfer bus off sensor is located NOT on the bus itself, but on the "center position" of the relay (the relay is magnetically attracted on the side with current - one of the two Generator busses - center position means not attracted by any side, thus open).
Resetting the Bus transfer switch may solve the problem.
If not, check the Transfer bus CIRCUIT BREAKER.
If it is popped, you have two options: resetting it or leaving it alone.
What to do?
We know the dangers of resetting a cb...
Since the real problem with this failure is losing one of the two pilots flight instruments, I suggest:
1) if in good weather, keep it popped, don't risk further electrical problems.
Pilots Flying becomes the non affected side. Easy.
2) if in IMC, better to have two pilots crosschecking each other.
Try ONE cb reset.
Note: with a Transfer bus cb popped, the amber light on the ovhd panel will be off!
Hower, you can easily recognise this typical scenario looking at the Aft fuel pumps lights... the one illuminated corresponds to the Transfer bus failed.
One more trick might work: if the relay cannot connect to his normal side, you can try forcing it to connect to the other side.
How?
Turning the Generator bus off on the affected side!
So far for a Transfer bus off. I'm not familiar with NG, but I'm afraid the conditions you stated in your initial post, Lucky Angel, are not correct.
Anyway, hope this can help.
LEM