Hello Tim,
Are you able to count the flash on the SEVCON ? You must have between 1 and 15 flashes (see in the attached file).
It is preferable to connect to the controller via the CAN bus and IXXAT's USB-to-CAN interface and DVTC software...
This is a very interesting case: propeller jamming. The drive will send the programmed maximum torque and wait for the motor to turn. The motor and the drive may heat up, so we should have a thermal cut-out, or a control law that says “STOP, the motor hasn't been running for too long...”.