Why does my dishwasher stop operating before the drain cycle?

Unable to diagnose the fault with my AEG dishwasher.

Dishwasher appears to operate as normal with one exception, when the drain motor needs to operate, the machine aborts the current programme and then goes into fault mode, leaving detergent/waste water in the sump. My workaround is to manually drain the sump by hand.

Have checked for blockages, and tested the drain motor while removed from the machine. If I mechanically remove the motor, but leave it connected I can see it operate as expected - it just won't spin when the cycle requires it to.

Am considering electrically isolating the motor from the machine and creating a separate circuit to operate the drain motor, with proper safety precautions in place.