Komori paper thickness driver error (S0406)

Can anyone help with this error on a Komori LS629? Paper thickness driver error (S0406), or paper thickness sensor error??

 

Press goes on impression with a motor. Motor failure is very rare. Impression home position sensors go out occasionally. Impression motor controllers also go out occasionally. Excessive squeeze is very common. So, will the error clear with power off for several minutes? Does the error occur during run?

 

Error will not clear by powering down. Did not happen while running. Error occurred as soon as I selected that unit for impression. I switch drivers with a Nother unit and problem stayed at original unit. So drivers were good. Home position sensor was a bout 6 mm away from flag on motor. I move sensor in two with in 1 mm of flag and it cleared the problem. Does anyone have a suggestion how the sensor got so far away from the flag??

 

Imp. Cyl. washing unit hit it while removing.