History: Worn drive units from pushing loads: no complained of no power and erattic take off. Rebuilt both drive units. Apon start up still exspeienced Right motor problems. Acting as thow a leg in the controller was open. Started receiving a 214R code. Trouble shot per manual. Found no external system concerns. Took and moved cables for left and right motors and trouble followed from the right motor to the left motor. Installed controller in a like unit and problem followed. Sent controller out to Flight systems for repair. Received unit back and followed instructions for installation and unit ran without any operational problems. Put unit on charger and now two days later I have a constant 214R at post. Followed trouble shooting once more and still no external concerns. I have a good key source voltage for key switch with voltage drop at.07v at wire 10 terminal C3, ground at c19 wire 103 voltage drop at.007v, resistance at the motor with cables was identical at.30 ohms for both motors and no shorts to frame. Any further Ideas that could be evecting this unit??????