Hi David,
Open coil on mode shifter assembly can be caused by the motor inverter sending excessive current to the mode shifter coil and opening the coil circuit. This can occur if you have lifted the lid during disengage and lift the lid again during engage for agitate or rinse.
In addition to the mode shifter assembly the motor inverter assembly has to be replaced too.
- The motor
Part number: WH20X10058 
Here are the breakdown diagrams and
Parts for GE WPRE6100G0WT Washer - AppliancePartsPros.com
Gene.