I need links diy video to fix it. I need a manual version also and images
A very quick Google search returned this gem in the first result.
The F51 error may indicate there is a MOTOR ROTOR POSITION SENSOR FAILURE (RPS). The sensor and control board has a connection or fault issue. This error can be cleared by cleaning/reconnecting the sensor OR replacing it. ... Simply disconnecting and reconnecting the sensor plug connection may fix the issue
There's also multiple reports of a centre-bolt on the base of the machine coming loose. If you've recently heard a knocking sound during agitation, this is the most likely cause.