Summary:
RBTC secondary contacts resistance. This solved Gen Split Problem
Hardware, corrosion at Load Meter Caused indication missmatch.
Cut, burned wire at battery contractor caused battery disconnect in flight.Multiple bad Duncan APU controlles did not help the troubleshooting
Detail:
Swapped CT ‘s on ground lugs at Baggage compartment, cleaned all hardware.
Swapped CT’s at gen B lead in Power panels, cleaned hardware.
Loose bolts at left gen RCR c
Found GCU pin K interconnect erratic when RBTC is tapped with a plastic screw driver.
Replaced both BTC’s as a precaution. This appeared to resolve the problem for a number of
flights.
Suspected Gens might be parallel correctly, with bad indication.
Evaluated D lead voltage on both starter generators. Found exact match from right to left D
lead. Under various load conditions.
Voltages roughly matched 1.2 to 1.6 volts per 300 amps expected (Jerry Cable, Duncan)
Swapped meters, split appeared to swap with meters for calibration.

Meters calibrated good, however, still split 25 in the airplane.

Found mixture of brass
and SS hardware at load meters was causing meter split. Replaced all with brass, and
meters now indicate exact gen load share correctly.

Left battery would intermittently disconnect.  found cut wire from the hot side of the Battery contactor touching lower skin.(batteries are relocated between MLG after Duncan APU install)Left contactor had been replaced previously.