LG WD-1238C front loader error OE

I have a problem with LG WD123C front loader that will only spin at lowest speed 400. If I select a higher spin speed it will start to accelerate to a spin then slows to a steady speed then stops. Drain pump seems to go on an on even though water has drained. machine keeps restarting spin cycle (over an hour or 2) and eventually comes up with OE drain eror. I have replaced main board & pressure sensor & checked no blockages. Sometimes after a number of restarts machine will do a high speed spin. If it wasnt for the OE message I would suspect an out of balance problem. Would be grateful for any help on what to check next.