TL2000 robotic communication fail

We are seeing an error with our TL2000 unit. 

error on the front panel:  Rob. Comm-Error

B2 03

we have upgraded firmware and drive software.  Tried a factory reset of all configuration.  Tried reseating the Library Control Card.  Bought a new Library Control Card.

None of this has helped.  it is obvious to us that the robotic arm is getting power (it has lights on it) but its not moving at all during initialization. 

any other ideas?