AOG with electrical problem - help please!

[robw]

All,

We have one of our planes stuck at a remote strip in Zambia with an electrical fault. Low voltage warning. Front and rear alternators won't engage. Tried resetting master. Tried standby master. Engaged/disengaged voltage regulators. Jiggled switches. Tried revving engines up to 2500. Tried tapping circuit breakers. Nothing helps. Probably got only one start left.

We are suspicious of a faulty generator field circuit breaker but ANY suggestions for things to try would be greatly appreciated.