yep edward i agree
one of the big culprits on these sitdown 3 wheelers is where the cables run under the battery tray through the frame. I believe that would be an ideal place to start :o)

I think we can say a couple of things; that both motors are turning under power in some times, which indicate the motors and brushes and SCR chopper panel are all working.
I agree that he may have to adjust the steering position potentiometer, but it does seem to be cutting out some of the contactor coils power at roughly the right spots. and therefore, it should run in straight ahead position if the contacts are all making good contact,
I am actually pretty sure he needs to get the manual (or compare to a 'sister' truck) to be able to confirm the location of the power cables for both motors and bus bars to contactors, his symptoms seem similar to those you may get if 2 of the connections are wrong and he is only getting power through the armature on one motor, but it is finding a return to the chopper panel (B-) through the other motors at rest contactor connection.
I would also strongly recommend to do the first step in troubleshooting as per GE, which is to confirm the "shorts to frame" are at least 100K ohms on any of the power cables and chopper panel heat sinks, as he may be getting power through the frame from damaged power cables.

i believe it's supposed to go like this
when fwd is selected both RF and LF contactors pull in during straight fwd travel.
when steered 90deg to the left LF drops out and LR kicks in to reverse the Left motor.

and if steered to the 90deg right then the opposite would happen RF contactor would drop out and RR would kick in.

if you were traveling in reverse the opposite would occur.

Now being this system has a potentiometer on the steer assy in the rear i would pay attention to the signal from this to the steering controller. Since the steering controller tells the contactors in what mode they are supposed to be in when in straight ahead and in turned conditions.

Do you have a service manual?
your going to need it to diagnose this problem effectively.
too many things going on at the same time to just be guessing at it. :o)

Yes both rf(right forward) and lf(left forward)contactors kick in the straight ahead position, but only the left side motor moves. When steering all the way to 90 only the rf(right forward)contactor kicks in, my understanding is when it reaches the 90 mark the lr(left forward)contactor is suppose to kick In but it doesn't only the rf(right forward ) contactors kick in.

one spot of confusion I have is that we actually have 4 contactors for a dual traction motor, lr, lf,[left motor reverse and forward] rr, rf [right motor reverse and forward] so in straight ahead forward the lf and rf contactors should pull in, in a tight right turn driving with the directional control lever in forward, the lf [left motor forward] contactor should stay pulled in, and as you turn the steering handcrank, the rf contactor should drop out, and as the turn gets tighter, the rr contact should pull in.
An 'armature' is the moving part in an electromagnetic device that is moved by the induced magnetism. in a forklift's contactor, the armature is the moving base that the moving contact is mounted upon [using insulators in this case]. contactors (the tips and the insulators) wear out and are replaced regularly. in a GE contactor, the armature has a guide pin in the base. if this pin works loose for any reason, you may not get complete closure of a 'when energized' contactor tip pair. if the insulators wear or rub a grove, you may get a failure to close the 'at rest' side of the contactor (the opposing direction contactor must be 'at rest' and completing the drive motor circuit0.

Dual motor truck, both contactors close but only the left hand motor moves. If I steer to one side all the way then the right had motor moves and only one contactor kicks in which is for the right side of the motors. So if in the straight ahead position only one motor moves, and both contactors kick in, if I turn wheel all the way one side then I get movement from the motor that does not move in the straight ahead positon.

I think you have to explain what this is doing in full detail.
Steering straight- what happens, do both directional motor contactors pull in?
Steering right then left- what happens, what works, what are the contactors doing?
Explain exactly what the forward and reverse contactors and left and right motors doing and when.

OK am still stuck, so far I've replaced drive motor, directional contactor, 2 and 5 rec, ac contactor and steer card. I don't have any codes, also does any one know what a armature contactor does, this contactor kicks in and out as soon as you hit the throttle, thanks

its probably the steering position board on top of the rear steering axle , the newer units have a steer position potentiometer.

i am not too framiliar with your machine but if it is dual drive there has to be a sensor or switches on the steering wheel somewhere (not the actual steering wheel but the rear tire that turns usually on top of the axle into the frame) that let the motor drive system know which drive motor to slow or stop depending on steer angle. i would be looking there.

Replaced both directional contactors and 2 and 5 recs. Still movement from right hand drive motor in the straight ahead position, motor moves when wheel moves all the way to one side, also had drive motor rebuilt. Need all the help I can get, thanks

replace all the directional contactors
Not just the tips, the entire assembly, you can keep the same coils if you want but the armature and or insulators can be your headache here, and while there is no warranty you fix the problem, you won't have them as an added problem. your problem is most likely in the "at rest" position of the contactor of the opposite direction.