LG Direct Drive plea for help

Hello All,
This is my first time on here and of course, I have a problem. The story so far: WM13220FD washing machine, belonging to my daughter ceased working and showed CE error. She called the local engineer out and he diagnosed main PCB failure. Trying to save her precious funds, I volunteered to fit a new one from ukwhitegoods. What could possibly go wrong? This was a different part number, but confirmed by Dave as the correct one. I fitted it easily (what a repairer-friendly design this machine seems to be)and tried the machine while daughter was on holiday. All seemed fine. Machine filled, started to wash normally, no fault, so drained and patted self on back. A day later, daughter returns with a mountain of washing, machine fills and tries to start, but drum just jumps several times, there’s a strange high-pitched squealing noise, the dreaded alarm chimes in and display now shows LE fault code. Air turns blue. The clue, I think, is that noise. Having tried the machine with top and rear covers removed, there is no bearing problem and the drum is totally free running until it jumps while trying to start. It appears magnetically locked for a while and then releases before trying again. The noise comes from the motor and I suspect is an inverter high frequency output. I couldn’t find much information here, but a google search found a youtube video showing the exact same jumping drum and strange noise. The guy there removed the rotor, checked the windings and hall sensor and found all correct. However, after reasembling, all worked normally. His best guess was that he moved the sensor slightly and inadvertently cured the fault. So there you have the sorry tale, or most of it. I’ve also been hit by my summer asthma and can’t breathe, but hey ho. Any pointers would be very gratefully received before I try to remove the rotor for a look.